The Feared Mosquito

It's one of those standard pub-quiz "trick" questions. What animal kills the most people? The hope is that contestants will nominate the 'obvious'—snakes, sharks, bears, whatever—before being blind-sided by the revelation that mosquitoes kill over a million people. They don't kill them directly, of course; their victims die from the diseases they spread*. The statistic also glosses over the point that there are many hundreds of species of mosquito that vary significantly in the nature and severity of their role as disease vectors. Nevertheless, for this post I'm considering the group that includes some of the most notorious vectors: the genus Anopheles.

*For the record, if the question was confined to active killings, the most dangerous animal to humans is other humans. Dogs come a distant second.

Anopheles punctipennis feeding, with the long palps extended in front of the head, copyright Nathan D. Burkett-Cadena/University of Florida.

Anopheles is one of the most divergent genera of mosquitoes, being placed in a distinct subfamily Anophelinae (along with a couple of small related genera) from the bulk of mosquitoes in the subfamily Culicinae. Adult Anopheles can be readily distinguished from culicine mosquitoes by their palps which are about as long as the proboscis (in other mosquitoes, the palps are distinctly shorter). Larvae of Anopheles lack the long respiratory siphons at the end of the abdomen found in other mosquito larvae so they rest parallel with the water surface rather than hanging below it. The genus is found around the world; over 450 named species are currently known (Harbach 2013) with many more waiting to be described. The genus is currently divided between seven subgenera though one of the largest of these, the cosmopolitan subgenus Anopheles, is not monophyletic. The remaining subgenera are better supported with the largest of these, Cellia, being found in the Old World. Between them, the subgenera Anopheles and Cellia account for over 400 of the known Anopheles species. The remaining small subgenera are mostly Neotropical with a single Oriental species being awarded its own subgenus.

Anopheles maculipennis, copyright Ryszard.

Anopheles is of most concern to humans, of course, for its role as a disease vector. As with other mosquitoes, the transmission of disease is done entirely by females taking blood meals to provide nutrients for their developing eggs. Males are not blood feeders, instead feeding entirely on sugar sources such as nectar (females also feed on nectar for their own nutrition). The main disease spread by Anopheles is malaria, but they may also spread malaises such as filariasis and arboviruses (Krzywinski & Besansky 2003). As noted above, species may vary significantly in their importance as disease vectors, even between quite closely related taxa. Many historically recognised vector "species" have proved, on close inspection, to represent species complexes of which some may be vectors and others not. For instance, one of the most important transmitters of malaria, the African A. gambiae, has been divided between at least eight different species (Coetzee et al. 2013). Misidentification of vectors can be a significant issue. For instance, mosquito control regimes in central Vietnam during the 1990s focused on two species, A. dirus and A. minimus, that were each active at different times of year. However, Van Bortel et al. (2001) found that A. minimus was in fact very rare in this area, with specimens previously thought to be A. minimus proving to be another species, A. varuna. Anopheles varuna is not a significant malaria vector, feeding almost entirely on animals such as cattle rather than on humans. Large amounts of resources would have been wasted trying to control a mosquito that was of little concern. What is more, the fact that malaria was not being transmitted by A. minimus raises the possibility that it was being spread by yet another species, one that had managed to escape attention. Remember, kids: bad taxonomy kills.

REFERENCES

Coetzee, M., R. H. Hunt, R. Wilkerson, A. Della Torre, M. B. Coulibaly & N. J. Besansky. 2013. Anopheles coluzzii and Anopheles amharicus, new members of the Anopheles gambiae complex. Zootaxa 3619 (3): 246–274.

Harbach, R. E. 2013. The phylogeny and classification of Anopheles. In: S. Manguin (ed.) Anopheles Mosquitoes: New insights into malaria vectors. InTechOpen.

Krzywinski, J., & N. J. Besansky. 2003. Molecular systematics of Anopheles: from subgenera to subpopulations. Annual Review of Entomology 48: 111–139.

Van Bortel, W., R. E. Harbach, H. D. Trung, P. Roelants, T. Backeljau & M. Coosemans. 2001. Confirmation of Anopheles varuna in Vietnam, previously misidentified and mistargeted as the malaria vector Anopheles minimus. American Journal of Tropical Medicine and Hygiene 65 (6): 729–732.

Apiocera: Flower-Loving Flies that Don't Particularly Care for Flowers

The insect world is full of animals that may be striking in appearance but about which we know relatively little. Such, for instance, are the flies of the genus Apiocera.

Male Apiocera, copyright Chris Lambkin.

Apiocera is a genus of a bit over 130 known species of relatively large flies, about half an inch to an inch in length, that are found in hot, arid habitats in disparate parts of the world: western North America, southern South America, southernmost Africa and Australia. Records of Apiocera from Borneo and Sri Lanka were regarded by Yeates and Irwin (1996) as probably errors. They are similar in their overall appearance to the robber flies of the family Asilidae, differing lacking the piercing mouthparts of robber flies or the moustache of bristles below the antennae. The venation of their wings is more similar to that of the mydas flies of the Mydidae, but they differ from most mydids in having shorter antennae and the regular triangle of three round ocelli on top of the head (Woodley 2009).

Observations of Apiocera species have been fairly few. A study of North American species by Toft & Kimsey (1982) found them to be restricted to sandy habitats with a fair amount of subsurface moisture, such as the shores of lakes and rivers or among sand dunes. The larvae, so far as we know, are similar to those of robber flies and are probably burrowing predators in the sand. Adults emerge from holes in the ground late in the growing season. In some places (such as Wikipedia), you may find Apiocera referred to as 'flower-loving flies' but visits to flowers are few. Toft & Kimsey (1982) found that the species they observed emerged after most plants had finished flowering and, indeed, questions have been raised historically as to whether adult Apiocera feed at all. Nevertheless, they may take honeydew from plant-sucking insects, and I will direct you to the photo below by Jean & Fred Hort that seems to show at least one Apiocera individual feeding at a flower. Males may congregate at certain locations, seemingly to form leks, though it is unclear whether they maintain territories. Toft & Kimsey (1982) noted that tussels between males of A. hispida were common, observing that "two males would make rapid contact in mid-flight, and stay together in a buzzing, tumbling ball for several seconds".

There seems to be little question that Apiocera and mydas flies are closely related. In fact, an analysis of Apiocera's phylogenetic relationships by Yeates & Irwin (1996) lead to a number of other genera that had previously been classified with Apiocera in the family Apioceridae being reassigned to the Mydidae (I suspect that it is the behaviour of these other 'apiocerids' that is behind the erroneous association of Apiocera with the 'flower-loving' moniker). Apioceridae is still maintained as a distinct family for Apiocera alone but, as noted by Woodley (2009), one could be forgiven for questioning whether Apiocera would be better treated as a very basal mydid. But that, of course, is simply a question of categories.

REFERENCES

Toft, C. A., & L. S. Kimsey. 1982. Habitat and behavior of selected Apiocera and Rhaphiomidas (Diptera, Apioceridae), and descriptions of immature stages of A. hispida. Journal of the Kansas Entomological Society 55 (1): 177–186.

Woodley, N. E. 2009. Apioceridae (apiocerid flies). In: Brown, B. V., A. Borkent, J. M. Cumming, D. M. Wood, N. E. Woodley & M. A. Zumbado (eds) Manual of Central American Diptera vol. 1 pp. 577–578. NRC Research Press: Ottawa.

Yeates, D. K., & M. E. Irwin. 1996. Apioceridae (Insecta: Diptera): cladistic reappraisal and biogeography. Zoological Journal of the Linnean Society 116: 247–301.

Ghost Moths and Other Obscurities

During my early years in rural New Zealand, I would often take note of the variety of insect life that could be seen coming to the screen doors at night, attracted by the light from inside the house. Among the most spectacular animals that would sometimes turn up was a gigantic pale green moth, about three inches long as it crawled across the screen. This was the puriri moth Aenetus virescens, perhaps New Zealand's best known member of the moth clade Exoporia.

Puriri moth Aenetus virescens, copyright Nga Manu Images NZ.

The Exoporia is one of the more basal moth groups alive today. The name of the clade refers to one of its most distinctive features: a female genital system with separate external openings for the seminal receptacle and the oviduct, meaning that the male's sperm has to travel along an external groove between the two if it is to fertilise the egg (in other Lepidoptera, there is a single cloacal opening, or there are separate openings but the cavities are connected by an internal duct). Other important features of the clade include dicondylic antennae, with two instead of just one articulations between the antenna and the head, and a male reproductive system without a sclerotised tubular intromittent organ (Kristensen 1978; the males instead have the gonopore opening on a shorter protuberance). Six families are generally recognised within the clade but the majority of species (including the puriri moth) belong to just one of these families, the Hepialidae, commonly known as the ghost moths.

Bentwing ghost moth Zelotypia stacyi, copyright CSIRO.

Hepialids definitely buck the phylogenetic trend among moths. Lepidopterists commonly divide the moth and butterfly order between two main groupings, somewhat self-explanatorily referred to as Micro- and Macrolepidoptera. To some extent, this is merely a division of convenience (the practicalities of working with smaller and larger moths can be quite different) but Macrolepidoptera is also used as the name of a major clade within the order with micro-Lepidoptera then indicated for any lepidopteran not belonging to this clade. By this measure, hepialids are by far the largest micro-Lepidoptera out there (most other examples are unquestionably micro). I've already alluded to the fifteen centimetre wingspan of the puriri moth but this isn't even close to being the largest hepialid out there. The honour perhaps goes to the bentwing ghost moth Zelotypia stacyi of eastern Australia which reaches a wingspan of 25 centimetres, a full ten inches. The larvae of hepialids are commonly borers in live trees; the puriri moth, for instance, gets its name because it burrows into puriri trees Vitex lucens. Other species live as larvae in burrows in soil, emerging at night to feed on pasture or leaf litter, or feeding externally on tree roots. Adult hepialids are short-lived and do not feed, and as such their proboscis is reduced or absent. They may emerge en masse at particular times of year. Following mating, females may scatter their eggs at random during flight or lay them in loose masses on the ground, with larvae finding a suitable food source after hatching. Because of the high mortality rates associated with this scatter-shot method, laying rates can be exceedingly large: females of some genera may produce around 18,000 eggs apiece (Nielsen & Common 1991).

Mnesarchaea acuta, copyright George Gibbs.

The other exoporian families are all much less diverse and more localised. They are also all small moths, far more typical 'micro-Lepidoptera'. The genus Mnesarchaea, endemic to New Zealand, retains functional mouthparts and is believed to be the sister group to all other exoporians. Larvae of Mnesarchaea live in silken galleries among mosses and liverworts, feeding on moss and liverwort leaves, algae, fungal spores and the like. The remaining families all lack functioning mouthparts as adults but their habits are otherwise all but unknown. Anomoses hylecoetes is placed in its own family known from rainforests in eastern Australia. The family Neotheoridae was until recently known from only a single female specimen collected in Brazil, but a few further species of this family were described recently by Simonsen & Kristensen (2017). Prototheora, another genus held worthy of its own family, is found in southern Africa. Finally, the family Palaeosetidae is known from a small number of genera with disjunct distributions in Colombia, south-east Asia and Australia. Because of its scattered distribution, some authors have questioned whether this last family is monophyletic, but an analysis of exoporian phylogeny by Simonsen & Kristensen (2017) continued to support it as such. It is not impossible that this family is more widespread, its apparent rarity due to the overlooking of small moths emerging for only very short periods, living just long enough to breed and deposit their eggs in as-yet-unknown locales.

REFERENCES

Kristensen, N. P. 1978. A new familia of Hepialoidea from South America, with remarks on the phylogeny of the subordo Exoporia (Lepidoptera). Entomologica Germanica 4 (3–4): 272–294.

Nielsen, E. S., & I. F. B. Common. 1991. Lepidoptera (moths and butterflies). In: CSIRO. The Insects of Australia: A textbook for students and research workers 2^nd ed. vol. 2 pp. 817–915. Melbourne University Press: Carlton (Victoria).

Simonsen, T. J., & N. P. Kristensen. 2017. Revision of the endemic Brazilian 'neotheorid' hepialids, with morphological evidence for the phylogenetic relationships of the basal lineages of Hepialidae (Lepidoptera: Hepialoidea). Arthropod Systematics and Phylogeny 75 (2): 281–301.

Midges of the Macabre

In a recent post, I commented that derived members of an insect 'order' could sometimes be all but unrecognisable as belonging to that order. Take a look at this:

Miastor sp., copyright Charles Olsen.

Believe it or not, sitting in the middle of that photo is a fully reproductively mature insect (I'm not so sure about the maturity of the other individuals). In fact, it's a fully mature fly. Miastor is a genus of midges found living in rotting wood or fungal fruiting bodies. Members of this genus are found worldwide; I believe that several species are recognised, but distinguishing the individual species is extremely difficult. Miastor exhibit what is called paedogenesis: they can become reproductively mature while still in the larval state. They are not the only genus of the family Cecidomyiidae to exhibit this process; another such genus, Oligarces, is found in similar habitats. Miastor is probably the best known such genus, in part because it has been cultured for study in the laboratory, and in part because of the decidedly macabre way in which its paedogenesis plays out.

Each paedogenetic Miastor larva develops several eggs within its ovaries (generally four to ten or more—Harris 1923). No males are involved in this process: the larvae are parthenogenetic as well as paedogenetic. These eggs hatch while still inside their mother, after which the daughter larvae are nourished by the mother's own tissues. Eventually, the daughters are not born so much as they escape. In the words of Quammen (1985), "While the food lasts, while opportunity endures, no Miastor female can live to adulthood without dying of motherhood". But karma still seems to have its place, because by the time the daughter larvae escape they carry their own fate within them: they emerge with their own eggs already developing inside them.

Metamorphosed male Miastor metraloas, copyright John Plakidas.

In this way, a Miastor colony can go through an entire generation in as little time as two weeks, until changing conditions (such as exhaustion of food supplies, or a change in season) induce a change in tack. Larvae are produced that do not reproduce paedogenetically in the way that their mothers did, but instead pupate in the usual way to emerge as more ordinarily formed midges, both males and females. As with another paedogenetic insect that has already been featured on this site, the beetle Micromalthus debilis, these metamorphosing larvae can be readily distinguished from paedogenetic larvae. Not only do they not produce the precocious reproductive organs of their fellows, but they have visible imaginal discs (the clumps of tissue that develop into adult structures during metamorphosis), and have eyes that are clearly separated on top rather than touching as in paedogenetic individuals (Harris 1923). After the mature adult midges emerge from their pupae, they can disperse in search of new habitats, seeking food for their offspring and mates for themselves in order to begin the cycle again.

REFERENCES

Harris, R. G. 1923. Occurrence, life-cycle, and maintenance under artificial conditions, of Miastor. Psyche 30 (3–4): 95–101.

Quammen, D. 1985. Natural Acts. Schocken Books.

ID for Heather?

The deadine for my crowdfunding drive has been extended. Thanks to your support, I am over 40% of the way towards success! But I'm still going to need everyone's help if I'm to be succesful. Please visit my page at Experiment.com and consider offering your support!

I was recently contacted by Heather Adamson who wanted to know if I could identify the animal in the above picture. She photographed it on an old post in the region of West Coolup, south of Mandurah here in Western Australia. I can tell her that it is some form of Lepidoptera larva (in other words, a caterpillar) and it looks like it may be beginning to weave itself a cocoon. Beyond that, I couldn't say. Do any of my readers have a better idea of what it is than I do?

Update: I shared this post to the Western Australian Insects group on Facebook, and Daniel Heald has suggested that Heather's photo may show the pupa of a lymantriid moth Teia athlophora. This species constructs itself a loose, cage-like cocoon from its own irritant hairs. The male, when he emerges, is a fairly standard looking brown moth, but the female is fat and flightless with only tiny stubs of wings. She will continue to live in and around her pupal cocoon, awaiting visits from courting males.

Juniper Gall Midges

Sometimes, the evidence of an insect's presence may be much more visible than the insect itself. Imagine passing by a common juniper tree Juniperus communis and seeing a structure like the one in the photo above (copyright Jean-Yves Baugnée). You might think it was some sort of reproductive structure. You would be right, though it is not the tree that is reproducing. This is the gall of a juniper gall midge Oligotrophus juniperinus, and were you to cut the gall in half you would possibly find a single gall midge larva lurking within. Many insects (and other animals) cause the development of galls on their host plants, thus providing themselves with both shelter and food in one convenient location.

Male Oligotrophus betheli, from Simova-Tošić et al. (2010).

The adult gall midge is a minute, very delicate fly, unlikely to be spotted by the casual observer. Gall midges are classified in the family Cecidomyiidae, an extremely diverse group of which not all members cause galls as larvae (some feed on plants without causing galls, others feed on fungi, a few are even predators or parasitoids). Cecidomyiids are divided between a number of subfamilies and tribes, with Oligotrophus belonging to the tribe Oligotrophini. In the past, this tribe has been used to cover a heterogeneous mix of relatively unspecialised cecidomyiids, but the most recent classification of the tribe strips it down to two genera, Oligotrophus and Walshomyia, found in the Holarctic region (Harris et al. 2006). Adults of these genera have legs with simple tarsal claws and long empodia (the soft pads between the claws), and as larvae they all live in galls on trees of the cypress family Cupressaceae. The exact form of the gall produced may differ between species, and it is often (though not always) possible to determine the species responsible for a gall by its form. For instance, three species that cause galls on Juniperus communis in Europe are Oligotrophus juniperinus, O. panteli and O. gemmarum. The first two species have galls formed from whorls of leaves pressed into a vase shape, but whereas in galls of O. juniperinus the leaves splay outwards towards the tip, in galls of O. panteli they remain parallel. The third species, O. gemmarum, has much smaller galls formed from only slightly modified buds; though very different from mature galls of the other two species, they may be confused with young undeveloped galls (Harris et al. 2006).

Despite their diversity, and the fact that some species are economically significant to humans, cecidomyiids are not a widely studied group. Part of the reason for this is that their small size and build makes them difficult to handle; diagnostic work on adults often requires slide-mounting them. I have made one not-very-successful attempt at slide-mounting cecidomyiids, and I can confirm that it is a fiddly process. Because the different body parts often have to be examined from different angles, slide-mounting first requires dissection of the animal into sections (so, for instance, the head can be placed on the slide face-on, the body side-on, and the terminalia top-up). In my experience, instructions for slide-mounting animals requiring such dissections will always tell you to arrange the various bits appropriately on the cover-slip before placing the slide (or the other way around, if you prefer). And if you know how to attach slide to cover-slip without having all your carefully arranged body parts immediately zooming off to a completely different spot on the slide from where you put them, then you're a far more skillful slide preparer than I am.

REFERENCES

Harris, K. M., S. Sato, N. Uechi & J. Yukawa. 2006. Redefinition of Oligotrophus (Diptera: Cecidomyiidae) based on morphological and molecular attributes of species from galls on Juniperus (Cupressaceae) in Britain and Japan. Entomological Science 9: 411–421.

Simova-Tošić, D., D. Graora, R. Spasić & D. Smiljanić. 2010. Oligotrophus betheli Felt (Diptera: Cecidomyiidae), a new species in the fauna of Europe. Arch. Biol. Sci. 62 (4): 1219–1221.

A Little Bit on Lesser Dung Flies

Copromyza stercoraria, photographed by Blaauw7.

The fly in the picture above is a typical member of the Sphaeroceridae, a family of over 1300 species of small flies that include some of the most ubiquitous of all insects. Despite their abundance, however, they rarely attract much attention from humans due to their small size, usually only about a couple of millimetres in length. Sphaerocerids are distinguished from other flies by the structure of the tarsus (the 'foot') on the hind leg. In most other flies, all the legs have the tarsi divided into elongate segments, but in sphaerocerids the first segment of the last tarsus is noticeably short and broad.

Sphaerocerids are sometimes referred to as 'lesser dung flies', referring of course to their small size and the diet of their larvae. However, lesser dung flies are not only associated with dung, but also feed on almost any form of decaying organic matter. They may be found on carrion or decaying vegetation or fungi. Some species may feed on a wide range of foodstuffs, but others are much pickier. One species, seemingly as yet unidentified, has been found in the excretory glands of a land crab. The coast-dwelling genus Thoracochaeta feeds on seaweed (Marshall & Buck 2010).

Podiomitra sp., photographed by Inna Strazhnik.

Though diverse, the majority of sphaerocerids are fairly conservative in appearance, including the Copromyza at the top of this post. There are, of course, notable exceptions. The individual just above is a representative of the Homalomitrinae, a rarely-collected subfamily of six known species in three genera from tropical Central and South America. The homalomitrines have a number of unusual features: their heads lack ocelli, have reduced bristles, and are more or less elongate; their thoraxes are relatively small; and the tarsi of all legs are short and broad. Two of the three genera, Sphaeromitra and Podiomitra, have markedly reduced venation in the wings. They do not have the appearance of strong fliers (though specimens have been collected in Malaise traps, indicating that they fly at least on occasion), but their extreme rarity (so far as is known) means that their lifestyles are almost unknown. Two species of Homalomitra, H. ecitonis and H. albuquerquei have been collected in association with army ants (Roháček & Marshall 1998), and it has been suggested that homalomitrines might develop in army ant middens, travelling phoretically by clinging to the ants with their modified tarsi (Marshall & Roháček 2003). However, it should be noted that this is largely speculative: the holotype of H. ecitonis, when collected, was reported to be walking amongst the supposed host ants, but otherwise little has been recorded of the nature of the association. It should also be noted that Roháček & Marshall (1998) suggested that H. ecitonis and H. albuquerquei form a clade to the exclusion of the other homalomitrine species, which further weakens confidence in extending the habits of these species to others.

There are also a number of species of sphaerocerid in which the wings are reduced or absent. The development of the wings may vary within a single species, as rather dramatically demonstrated by the specimen of Pullimosina meijerei shown above in a figure from Roháček (2012). This male exhibited unequal wing development, with the left wing that of a brachypterous individual but the right wing that of a macropter.

Sphaerocerids have been suspected as potential disease vectors due to their association with waste and decay, but actual evidence of negative impact on humans is rare. There appears to be at least one recorded case of sphaerocerid-caused intestinal myiasis (Marshall & Richards 1987), and sphaerocerids may become numerous enough to be a nuisance in places with a concentration of potential food, such as abattoirs or mushroom farms. Whatever their negative impacts may be, they are almost certainly outweighed by the positive: the ubiquitous sphaerocerids are probably major players in the process of breaking down waste materials and returning nutrients to the environment. They're the little flies that save you from being knee-deep in shit.

REFERENCES

Marshall, S. A., & M. Buck. 2010. Sphaeroceridae (small dung flies). In: Brown, B. V., A. Borkent, J. M. Cumming, D. M. Wood, N. E. Woodley & M. A. Zumbado (eds) Manual of Central American Diptera, vol. 2, pp. 1165-1187. NRC Research Press: Ottawa.

Marshall, S. A., & O. W. Richards. 1987. Sphaeroceridae. In: McAlpine, J. F. (ed.) Manual of Nearctic Diptera, vol. 2, pp. 993-1006. Biosystematics Research Centre: Ottawa.

Marshall, S. A., & J. Roháček. 2003. Podiomitra, a new genus of Homalomitrinae (Diptera: Sphaeroceridae) from Costa Rica. Proceedings of the Entomological Society of Washington 105 (3): 708-714.

Roháček, J. 2012. Wing polymorphism in European species of Sphaeroceridae (Diptera). Acta Entomologica Musei Nationalis Pragae 52 (2): 535-558.

Roháček, J., & S. A. Marshall. 1998. Revision of Homalomitrinae subfam. n. (Diptera: Sphaeroceridae), with the description of a new genus and three new species. European Journal of Entomology 95: 455-491.

Beetle Flies

Unidentified celyphid, photographed by Giovzaid85.

Those of you who follow me on Twitter (@CatofOrg) may have already seen these guys, but I thought it worth putting them up here as well. Because sometimes you come across an animal that just makes you stop, blink, and exclaim, "What the creeping jayzus is that!". Ladies and gentlemen, the Celyphidae.

Another celyphid, photographed by Melvyn Yeo.

Celyphids are flies that are doing their damnedest to look like a beetle (and are hence, unsurprisingly, commonly known as beetle flies). The scutellum, which in most flies is a relatively small lobe of the thorax sitting behind and between the wings, has become massively enlarged and overtops the abdomen. The wings (which are full-sized and fully functional) slip in underneath the scutellum when folded back. Just to add to the overall beetle-osity of the thing, celyphids can be very shiny and metallic (check out the blue-black item here). The function of this giant scutellum is unknown; protection is the first thing that comes to my mind, but I don't know if the scutellum is any more sclerotised than the rest of the animal. One suggestion that has apparently been made is that the scutellum may provide extra buoyancy in flight (Tenorio 1972), to which I ask, is it hollow or something?

Photo by Meng Foo Choo.

Celyphids are found in tropical Asia and Africa (all the photos on this page except the last were taken in Singapore). They are closely related to the more widespread family Lauxaniidae, and have been treated by at least some authors as a derived subgroup of the latter (some lauxaniids also show a degree of enlargement of the scutellum). The larvae of celyphids feed on rotting vegetation.

Celyphus koannanius, from here.

REFERENCE

Tenorio, J. M. 1972. A revision of the Celyphidae (Diptera) of the Oriental Region. Trans. R. Ent. Soc. Lond. 123 (4): 359-453.

Yponomeutoids and their Boring Larvae

...because some puns will never die.

Larvae of the bird-cherry ermine moth Yponomeuta evonymella, from here.

As noted in an earlier post, most people's perception of Lepidoptera, 'butterflies and moths', is heavily skewed towards the larger members of the group while the greater diversity is actually to be found among the smaller species (this sentence, offhand, could be repurposed for just about any animal group). The subject of today's post, the Yponomeutoidea, are a clade of about 1800 species of the much-overlooked smaller Lepidoptera. Yponomeutoids have been recognised as a group primarily on the basis of a single synapomorphy, the presence of posterior lobes on the eighth abdominal pleura (a 'pleuron' being a sclerite on the side of the body wall). This character has been secondarily lost in some subgroups of the Yponomeutoidea, but the clade is also supported by molecular data (Sohn et al. 2013). The larvae of yponomeutoids are plant-feeders, with the clade including some species that feed internally as leaf-miners or stem-borers, and others that feed externally on leaves though they do conceal themselves within a silk webbing. A number of species are effectively both, starting out as internal leaf borers then changing to external leaf webbers as they grow larger. Some species are notable horticultural pests, such as the diamondback moth Plutella xylostella that attacks brassicas*.

*Horticulture is the only human endeavour in which you will hear something described as 'attacking' a cabbage.

Apple leaf miner Lyonetia clerkella, photographed by Jeff Higgott.

The most recent review of the clade's systematics by Sohn et al. (2013) recognised eleven families within the Yponomeutoidea, but this was not the first re-organisation of the yponomeutoids and it will probably not be the last. Many of the families have few distinct synapomorphies, and a few recognised by Sohn et al. lack recognised morphological synapomorphies altogether and are united by molecular analysis only. Most yponomeutoids follow the usual microlepidopteran pattern of being small and generally brown, but there are some exceptions. The 'mega-plutellids' of New Zealand and Tasmania (placed by Sohn et al. in the family Glyphipterygidae rather than Plutellidae) are relatively large, with the Tasmanian Proditrix nielseni having a wingspan of over six centimetres (McQuillan 2003). The adult of the ailanthus webworm Atteva pustulella has a fairly striking array of black-ringed white patches on an orange background.

Galapagos bitterbush moth Atteva hysginiella, photographed by Rich Hoyer.

Though the clade is diverse in its habits overall, feeding habits tend to be conserved within each of the constituent families. It is not entirely clear whether internal or external feeding represents the original lifestyle of the yponomeutoids, though there may be a slight tip towards internal feeding. If this is the case, then external feeding has arisen within the yponomeutoids on a number of occasions, and the pine needle miners of the genus Zelleria in the family Yponomeutoidea probably represent at least one case of a internal feeder derived from externally feeding ancestors. Some families show a bias towards particular plant hosts: the Attevidae are primarily found on Simaroubaceae, while the Bedeliidae show a preference for Convolvulaceae. Others are more diverse in their selection.

REFERENCES

McQuillan, P. B. 2003. The giant Tasmanian ‘pandani’ moth Proditrix nielseni, sp. nov. (Lepidoptera: Yponomeutoidea: Plutellidae s. l.) Invertebrate Systematics 17: 59-66.

Sohn, J.-C., J. C. Regier, C. Mitter, D. Davis, J.-F. Landry, A. Zwick & M. P. Cummings. 2013. A molecular phylogeny for Yponomeutoidea (Insecta, Lepidoptera, Ditrysia) and its implications for classification, biogeography and the evolution of host plant use. PLoS One 8(1): e55066. doi:10.1371/journal.pone.0055066.

Deceptive and Poisonous Sisters

Iphicleola sister Adelpha iphicleola, photographed by Arthur Chapman.

The butterfly genus Adelpha includes 85 species, many with multiple subspecies, found widely in North and South America (Willmott 2003a). Some of you may recognise 'adelpha' as the Greek word for 'sister', which is also the vernacular name for these butterflies. Supposedly, the white stripes on the wings of many species resemble the edges of a nun's habit (or, at least, so sayeth Wikipedia). The sisters belong to a group of butterflies called the Limenitidini, members of which tend to sit with their wings open when resting, and have a distinctive gliding flight pattern in which the wing tips are pointed downwards (Willmott 2003b). Adelpha is the only genus of Limenitidini found in South America. In North America, Adelpha bredowii is found as far north as Oregon, while in South America species are found down to Uruguay. Not surprisingly, the highest diversity is found in the tropics, though some species are relatively uncommon throughout their ranges (Willmott 2003a).

As caterpillars, Adelpha species feed on a wide variety of food plants, with individual species varying from very host-specific species to broadly catholic species. As befits Neotropical caterpillars, some species possess a ludicrous array of protrusions and outgrowths:

Caterpillar of Adelpha serpa selerio, photographed by Artour A.
When feeding on a leaf, the caterpillars leave the midrib intact, and use it as a support when resting. Over time, they extend the midrib using a combination of faecal pellets and silk to extend their support, and they also sit on this support when moulting. After moulting to the final larval instar, they leave the support and rest on the upper leaf surface. They also attach masses of mixed silk and faecal pellets to the base of their support or hanging off it. One species, Adelpha basiloides, builds small, curved, larva-shaped faecal masses that it places on the leaf surface several millimetres away from its support: Aiello (1984) speculated that these might functions as decoys to distract potential predators from the real caterpillar.

Arizona sister Adelpha eulalia, photographed by Tom Bentley.

The adults of Adelpha have a reputation for being tricky to identify; DeVries described them as "the most difficult and trying taxonomically of all the nymphalids". For a long time, Adelpha species were divided into groups on the basis of their wing patterning, but comparisons with other features such as caterpillar morphology have revealed that species with similar wing patterns are often not closely related (Aiello 1984; Willmott 2003b). Instead, it has been suggested that mimicry has been a significant factor in the genus' evolution: certain species feeding as caterpillars on toxic plants such as members of the Rubiaceae (and hence sequestering the plant toxins to render themselves distasteful) are imitated by species with more innocuous diets. Because the appropriate model for such mimicry may vary with distribution, some mimetic species are quite variable in appearance; prior to the genus' revision by Willmott (2003a), some members of a single species were classified in entirely separate species groups!

REFERENCES

Aiello, A. 1984. Adelpha (Nymphalidae): deception on the wing. Psyche 91 :1-46.

Willmott, K. R. 2003a. The Genus Adelpha: Its systematics, biology and biogeography (Lepidoptera: Nymphalidae: Limenitidini). Scientific Publishers.

Wilmott, K. R. 2003b. Cladistic analysis of the Neotropical butterfly genus Adelpha (Lepidoptera: Nymphalidae), with comments on the subtribal classification of Limenitidini. Systematic Entomology 28: 279-322.

Colour vs Crypsis

The southeast Asian Lyssa zampa, a large nocturnal uraniine. Photograph by Alexey Yakovlev.

Even if you don't know much about insects, you've probably been taught the difference between a butterfly and a moth. Butterflies are ornate, colourful and active during the day, while moths are... ornate, colourful and active during the day?

A cryptic epiplemine Crypsicoela subocellata, photographed by Stephen Luk.

The Uraniidae are a family of about 700 species of mostly pantropical moth. The family is united primarily by their distinctive sexually dimorphic tympanal organs: in females, the tympanal organs open ventrally on the first abdominal sternite (as in a number of other moths), but in males they open dorsally or laterally at the junction of the second and third segments (Scoble 1995). About 600 of the 700 species of uraniid are assigned to the subfamily Epipleminae, and are generally nocturnal, brown and cryptic. Many epiplemines roll their wings up when at rest, so that they resemble a small brown stick.

The South American migratory Urania fulgens. Photo from here.

However, some members of the subfamily Uraniinae have become diurnal. These diurnal species have brightly iridescent wings with prominent tails, and have often been compared to swallowtail butterflies. One of the best-known species is Urania fulgens, a South American species that migrates north into Central America at certain times of year. Migrating individuals may reach as far north as the southern United States.

REFERENCES

Scoble, M. J. 1995. The Lepidoptera: Form, function and diversity. Oxford University Press.

Freak of the Week: Wingless, Legless Flies

I found this while looking up identification info for phorid flies, of which we currently seem to be receiving something of an influx in our samples.


Photoes from here.

Most of what you see in the lower of the two photoes above are larvae of army ants of the genus Aenictus. The odd one out is the whiter 'larva' in the centre—which is not a larva at all, but a fully adult female of the phorid fly Vestigipoda longiseta! (The upper photo shows the same animal in close-up.) This bizarre animal makes its living by imitating its host larvae and being fed by the larvae's deluded carers. Five species of Vestigipoda have been described to date from Malaysia (Disney et al., 1998; Murayama et al., 2008).


Close-up of head of Vestigipoda maschwitzi, from Disney et al. (1998).

Cases of neoteny, where insects develop full sexual maturity while still 'larvae', are not unknown among holometabolous insects (I earlier described a case involving the beetle Micromalthus). However, Vestigipoda cannot be regarded as neotenous because the female has a fully developed adult head.

So far, Vestigipoda seems to only be known from females. It is possible that males, when found, may turn out to be much more normal phorid flies. The challenge would be recognising them as related to their bizarre females.

REFERENCES

Disney, R. H. L., A. Weissflog & U. Maschwitz. 1998. A second species of legless scuttle fly (Diptera: Phoridae) associated with ants (Hymenoptera: Formicidae). Journal of Zoology 246 (3): 269-274.

Maruyama, M., R. H. L. Disney & R. Hashim. 2008. Three new species of legless, wingless scuttle flies (Diptera: Phoridae) associated with army ants (Hymenoptera: Formicidae) in Malaysia. Sociobiology 52 (3): 485-496.

Blues (Not All of Them Blue) (Taxon of the Week: Polyommatus)

I'm heading into the field tomorrow for two weeks and won't be able to respond to comments on this post, so I'll just give you a light coverage for the latest Taxon of the Week, the butterfly genus Polyommatus:


Male of the blue butterfly Polyommatus escheri, a widespread species in Europe. Photo by Eric Sylvestre.

Polyommatus is a genus of about 200 species of butterfly found in Eurasia and northernmost Africa with the highest diversity seemingly around west central Asia from Turkey to Iran. It is divided into a number of subgenera (recognised as separate genera by some authors) with the largest, Agrodiaetus, including about 130 species (Wiemers et al. 2010). As the common name 'blue' would suggest, the males of most species are a brighter or paler shade of blue; females are generally brown.


Female of Polyommatus semiargus (or Cyaniris semiargus). Photo by James Lindsey.

The majority of Polyommatus species lay their eggs on plants of the family Leguminosae. Like many other species of the family Lycaenidae to which they belong, caterpillars of Polyommatus show an association with ants. In the species in which this association has been most studied, the common blue P. icarus, the association is facultative only; the caterpillars may reach maturity without ever being tended by ants (other lycaenid species may require tending to survive).


Female of Polyommatus agestis. Photo by Hans-Peter.

When the caterpillar of Polyommatus icarus reaches its fourth instar, it starts producing honeydew from an organ on its abdomen. It will also produce vibrations that travel through the ground and may attract ants. Arriving ants are presented by the caterpillar with honeydew, in return for which they tend the caterpillar and protect it from predators and parasitoids. The caterpillar also possesses a pair of eversible tentacles on either side of the honeydew organ that it displays when it registers the presence of ants; displaying the tentacles seems to encourage attention from the ants somehow, perhaps by releasing pheromones (Axén et al. 1996). When the caterpillar moults into a chrysalis, the ants bury it under a light covering of soil and leaf litter where it remains until the adult butterfly emerges after two weeks.


Polyommatus ainsae (or Agrodiaetus ainsae), an inhabitant of northern Spain. Photo by Teresa Farino.

REFERENCES

Axén, A. H., O. Leimar & V. Hoffman. 1996. Signalling in a mutualistic interaction. Animal Behaviour 52: 321-333.

Wiemers, M., B. V. Stradomsky & D. I. Vodalazhsky. 2010. A molecular phylogeny of Polyommatus s. str. and Plebicula based on mitochondrial COI and nuclear ITS2 sequences (Lepidoptera: Lycaenidae). European Journal of Entomology 107: 325-336.

More than Just Sophophora (Taxon of the Week: Drosophilidae)

The variety of drosophilids, from here. In the classification used in this post, the species illustrated would be Sophophora simulans and Idiomyia conspicura.

Today's Taxon of the Week is a group of which one particular species has already occupied a reasonable chunk of screen time at this site. The recent taxonomic controversy over Sophophora melanogaster* has been covered here, here and here, and I'm sure that by now we're all well and truly sick of the horrid little beast. The Drosophilidae is a family of some 3500 species of which S. melanogaster is but one. Surely it's time some of the other drosophilids were given their dues?

*As noted in earlier posts, there is really no justification for including the Sophophora species in the genus Drosophila. Even if you subscribe to a classificatory theory that forgives paraphyly, there are simply too many non-Drosophila genera separating Sophophora from Drosophila sensu stricto to make including the latter in one genus reasonable (see Linde et al., 2010, and various other references mentioned therein). It's like the entomological version of West and East Pakistan. [facetious snark] So now the decision about appropriate naming has been officially made, can we please all get over it and deal with the consequences? [/facetious snark]

Drosophilids are treated as part of a large grouping of flies known as the acalyptrates. Acalyptrates possess short antennae with a horseshoe-shaped fissure between the antennae and the upper part of the face but lack a calypter, a lower lobe at the base of the wing found in houseflies and blowflies. Distinguishing the various acalyptrate families from each other can be an absolute nightmare (I speak from painful experience) but the features of Drosophilidae include an incomplete subcostal vein in the wing, three (occasionally two) pairs of bristles on the face with the front pair pointing forwards and the remainder pointing backwards, and usually no bristles on the anepisternum (one of the side plates on the thorax) (Grimaldi, 1990).


Pair of Drosophila endobranchia courting on the carapace of the land crab Gecarcinus ruricola whose mouthparts will become home to their commensal larvae. From Stensmyr et al., 2008.

Most drosophilids are small flies (the largest belong to the genus Idiomyia and have wingspans of up to two centimetres). The majority of species feed as larvae on yeasts and the like growing on decaying plant matter but a number are more outré in their dietary habits (Ashburner, 1981). Scaptomyza larvae mine leaves while larvae of Lissocephala powelli, Drosophila carcinophila and D. endobranchia live as commensals on the mouthparts of land crabs, feeding on the bacteria growing there. Several species of various genera are predatory, mainly on small plant-sucking bugs such as scales and whiteflies though other targets are known (including two unrelated species feeding on frog eggs and at least one record of larvae of a generalist species taken from a secondarily infected wound of a surgery patient). The Drosophila simulivora group includes four West African species whose larvae are aquatic predators of midge and sandfly larvae. Perhaps the most incredible carnivorous drosophilid is the European Cacoxenus indigator which lays its eggs in the brood cells of the mason bee Osmia coerulescens. The mason bee arranges its cells in single file in a long tube and the female Cacoxenus will insert a single egg into each cell except the last. The fly larva feeds on the food stores left for the bee larva and eventually on the bee larva itself (though it is unclear whether the fly actually attacks the bee while it is alive or simply scavenges it after it dies from strarvation, as it has been known for the bee and fly to both emerge alive from a single cell). The reason the female Cacoxenus does not lay in the terminal cell is that, once her own larvae pupate into adult flies, they are unable to break free of the brood cell themselves and are dependent on the one surviving bee to release them as it frees itself from the nest.


Two males of the hammer-head fly Idiomyia heteroneura performing competitive displays. This is an endangered species with a restricted range on the island of Hawai'i. Photo from here.

The highest concentration of drosophilid diversity is found in the Hawaiian islands which are home to perhaps more than 1000 species (O'Grady et al., 2003) divided between the genera Scaptomyza and Idiomyia (the latter referred to by many authors as "Hawaiian Drosophila"). Many of these species, it should be noted, are exceedingly rare and localised and many remain undescribed. Molecular analysis indicates that the Hawaiian drosophilids form a single clade, indicating a single colonisation of the island (O'Grady & DeSalle, 2008). However, Scaptomyza also includes a number of continental species that appear to be derived from a Hawaiian ancestor.

REFERENCES

Ashburner, M. 1981. Entomophagous and other bizarre Drosophilidae. In The Genetics and Biology of Drosophila vol. 3A (M. Ashburner, H. L. Carson & J. N. Thompson, eds) pp. 395-429. Academic Press: London.

Grimaldi, D. A. 1990. A phylogenetic, revised classification of genera in the Drosophilidae (Diptera). Bulletin of the American Museum of Natural History 197: 1-139.

Linde, K. van der, D. Houle, G. S. Spicer & S. J. Steppan. 2010. A supermatrix-based molecular phylogeny of the family Drosophilidae. Genetics Research 92: 25-38.

O'Grady, P., J. Bonacum, R. DeSalle & F. Do Val. 2003. The placement of Engiscaptomyza, Grimshawomyia, and Titanochaeta, three clades of endemic Hawaiian Drosophilidae (Diptera). Zootaxa 159: 1-16.

O'Grady, P., & R. DeSalle. 2008. Out of Hawaii: the origin and biogeography of the genus Scaptomyza (Diptera: Drosophilidae). Biology Letters 4: 195-199.

In Which, Despite Not Being The Crowd Favourite, Drosophila funebris Holds D. melanogaster Down and Kicks It Repeatedly in the Teeth

The original and still reigning champion, Drosophila funebris. Fear it, I say! Photo by Nicolas Gompel.

It's been two years in the making, but the ICZN decision on Drosophila has finally been announced (ICZN, 2010). You may recall that an application had been submitted (Linde et al., 2008) to make Drosophila melanogaster, the subject of countless genetic studies, the type species of the genus instead of the current holder of that title, D. funebris. See previous posts here and here for background details.

And the verdict: by a surprisingly large margin (23 to 4, with one absence), the Commission has turned the proposal down. Drosophila funebris remains the valid type species of the genus; D. melanogaster retains the potential for reclassification. Those of you with a particular interest in the workings of nomenclature* would do well to get hold of a copy of the decision. In light of the higher than usual public interest in this case, the unusual step has been taken of publishing individual comments from each of the commissioners on the reasoning behind their decisions. As well as the insight provided into this particular case (and it's worth noting that some of the commissioners on both sides of the floor ended up voting against their own initial sympathies), some of the comments provide interesting talking points about the role of nomenclature in general.

*Yes, we do exist. I'm afraid the doctors say that there's nothing they can do.

Some of the reasons given for voting against the proposal were reasonable, others less so. A. small number of commissioners voiced the complaint that the proposal was asking the ICZN to endorse a particular taxonomic method; as I argued in one of the previous posts, it did no such thing and I am rather disappointed that this issue was raised. Some commissioners also turned down the proposal on the grounds that it was premature (Miguel Alonso-Zarazaga stated that he "felt that the authors of the case had not allowed the community to have a healthy discussion of their proposals, since the ‘detailed phylogenetic studies’ mentioned in the case were still largely unpublished, and were thus hypothetical"). However, while the proposal may have been precipitated by an as-yet unpublished study, the results of that study are hardly novel. As pointed out by László Papp in his comments on his supporting vote, the issue that any subdivision of Drosophila would require the removal from that genus of D. melanogaster has been under discussion for at least 35 years (a time when, I should note, purely phylogenetic considerations were often considered less significant).

Less trivial are the concerns that the proposal introduced a higher overall nomenclatural instability than the current status quo and that it may have set an uncomfortable precedent. The commission was being asked to choose between maintaining Drosophila for a smaller number (about 300) of species including some very well-known taxa, or a potentially much larger number (up to about 1100) of mostly less familiar species. Should "celebrity names" carry that much greater weight? Also, while the combination Sophophora melanogaster may be unfamiliar, there is no actual ambiguity about to what it refers.

Some commissioners, as well as many of the ICZN's press statements, raised the argument that "drosophila" could still be used as an informal name for Sophophora melanogaster. True, as far as it goes, and not unprecedented: names such as "azalea" and "cosmos" continue to be used despite the genera of those names being stricken from the technical literature long ago. Nevertheless, this is not anywhere near a satisfactory solution. As a corollary example, a number of recent authors have proposed restricting "Aves" to the crown group of birds on not unreasonable grounds. The supposed divide between technical and vernacular names has done nothing to dissuade people from objecting to the idea that creatures such as Archaeopteryx and Ichthyornis may no longer be "birds".

My thanks go to Kim van der Linde (first author of the proposal) and Elinor Michel (secretary of the ICZN) for sending me copies of the decision. Kim's own reaction to the ruling can be read here.

REFERENCES

Linde, K. van der, G. Bächli, M. J. Toda, W.-X. Zhang, Y.-G. Hu & G. S. Spicer. 2007. Case 3407: Drosophila Fallén, 1832 (Insecta, Diptera): proposed conservation of usage. Bulletin of Zoological Nomenclature 64 (4).

More in the Bloodsucking Vein (Taxon of the Week: Simulium)

Female Simulium feeding. Photo by maz_nat.

Blackflies of the genus Simulium (including several hundred species - see Adler & Crosskey, 2008, for a listing if you're really keen) are found around the world and familiar to most people for their blood-sucking habits. Like other members of the fly clade Culicomorpha, such as mosquitoes and chironomid midges, the larvae of blackflies are aquatic filter-feeders while only the females feed on blood as adults. In fact, blackflies (like other culicomorphs) are primarily nectar- rather than blood-feeders. Both males and females feed on nectar as adults and the females may require only a single blood meal to complete development of their eggs (Cupp & Collins, 1979).


Simulium larvae in a stream. The close-up photo is of the head of a filter-feeding larva. Photo from here.

Which is not to say that the role of blackflies as parasites is negligible. Askew (1971) refers to a plague of Simulium columbaschense in 1923 causing the deaths of nearly 20,000 head of livestock along the banks of the Danube. The most notorious blackflies are members of the Simulium damnosum complex of Africa (with one species, S. rasyani, in Yemen) which carry the human-parasitic worm Onchocerca volvulus. As well as the debilitating skin disease infection with Onchocerca causes in the majority of cases, approximately 250,000 people are rendered blind by Onchocerca infections every year. The various species of the Simulium damnosum complex are largely indistinguishable externally and require examination of their chromosome arrangements to be identified; however, different species differ significantly in their potential as Onchocerca vectors. Some 55 'species' have been identified in the complex, making it one of the largest known assemblages of cryptic species (Post et al., 2007).

REFERENCES

Adler, P. H., & R. W. Crosskey. 2008. World blackflies (Diptera: Simuliidae): a fully revised edition of the taxonomic and geographical inventory. http://blackflies.info/sites/blackflies.info/files/u13/blackflyinventory_2008_Adler___Crosskey_1.pdf. Accessed 23 March 2010.

Askew, R. R. 1971. Parasitic Insects. Heinemann Educational Books: London.

Cupp, E. W., & R. C. Collins. 1979. The gonotrophic cycle in Simulium ochraceum. American Journal of Tropical Medicine and Hygiene 28 (2): 422-426.

Post, R. J., M. Mustapha & A. Krueger. 2007. Taxonomy and inventory of the cytospecies and cytotypes of the Simulium damnosum complex (Diptera: Simuliidae) in relation to onchocerciasis. Tropical Medicine and International Health 12 (11): 1342-1353.

Caterpillars and their Capers (Taxon of the Week: Belenois)

The brown-veined white, Belenois aurota, of southern Africa. Photo from Bronberg Conservancy.

Belenois is a genus of about thirty species of butterfly of the family Pieridae found in tropical and subtropical regions of the Old World, with the greatest concentration of species in Africa. The caterpillars feed on plants of the caper family Capparaceae, though Moulds (1999) suggested that early records of 'cabbage whites' feeding on Brassica species in Australia prior to the confirmed introduction of any Pieris species might refer to Belenois java (the families Capparaceae and Brassicaceae are very closely related). Like most other pierids, Belenois species are medium-sized butterflies (the sole Australian species, B. java, has a wingspan of 55 mm - Braby 2000) with white or yellow background coloration patterned with black or brown on the wings. Individuals of a single species may vary in coloration patterns. Studies on B. java teutonia, which has distinct dark and pale forms, found that larval food species was one factor potentially affecting variation - caterpillars raised on Capparis umbonata always emerged from their pupae as dark form individuals, caterpillars from C. lasiantha were always pale, while caterpillars from C. spinosa could be either dark or pale (Braby, 2000).


The African veined white, Belenois glidica abyssinica. Photo by Johan van Rensburg.

Migratory habits have been recorded for a number of Belenois species, particularly B. java in Australia and B. aurota in southern Africa. Belenois aurota is one of the most abundant butterfly species within its range - one observer recorded witnessing a migration of about 500,000 individuals in Lesotho (Kopij 2006). A number of females will lay their eggs together in loose clusters on a suitable host plant. Braby (2000) notes that in some seasons a single tree may carry tens of thousands of eggs of B. java and the tree may end up being completely defoliated by the voracious caterpillars. Mortality among the caterpillars is high; only a few will reach adulthood.


The caper white, Belenois java teutonia, of Indonesia, New Guinea and Australia. Other subspecies of this species are found on islands of the Pacific. Photo by Peter Shanks.

REFERENCES

Braby, M. F. 2000. Butterflies of Australia: their identification, biology and distribution vol. 1. CSIRO Publishing: Collingwood (Australia).

Kopij, J. 2006. Lepidoptera fauna of Lesotho. Acta Zoologica Cracoviensia 49B (1-2): 137-180.

Moulds, M. S. 1999. The history of Australian butterfly research and collecting. In Biology of Australian Butterflies (R. L. Kitching et al., eds) pp. 1-24. CSIRO Publishing: Collingwood (Australia).

Name the Bug: Boreus

Boreus sp. Photo by A. Staudt.

Boreus is the main genus in the family Boreidae, a holometabolous insect family found in the northern parts of Eurasia and North America. Boreids are active during winter, when they are found among patches of moss on which they lay their eggs or on snow drifts between mossy rocks. Their apparent affinity for snow (the main source of moisture in the cold but dry habitats they prefer) together with their jumping movement gives them the common name of "snow fleas". Boreids also resemble fleas in effectively lacking wings - females lack them entirely, while males have the wings highly modified into a pair of large stiff hooks over the back (the individual in the photo above is a male). These hooks are, of course, useless for flying, but are used by the male in mating. As described by Cooper (1974): "An ardent male, when within some millimeters range, springs at the female, ensnaring her with his tong-like wings while seizing whatever he can of her extremities with one or both of his genital claspers". After the male's grip on the female has been secured (not always a simple process - see Cooper, 1974, for fuller details) and their genitalia have been conjoined, he may carry her about on his back in the mating position for several hours (the hook-wings are not actually used to hold the female while mating, only in the initial grab).

Most authors have included the Boreidae in the order Mecoptera, the scorpionflies. However, both molecular and morphological data have indicated that the Mecoptera as traditionally recognised are paraphyletic - from a phylogenetic perspective, the Siphonaptera (fleas) definitely and the Diptera (flies) possibly can be regarded as mecopterans. As a result, some authors have proposed restricting Mecoptera to a monophyletic core (the panorpoid families) and removing the families Boreidae and Nannochorista (a Gondwanan genus whose larvae are aquatic predators in streams of chironomid fly larvae) each to a separate monofamilial order. Both molecular and morphological data agree that the boreids are the sister group to the fleas (Grimaldi & Engel, 2005), making the name "snow flea" rather prescient. An alternative suggestion by Novokshonov (2002) that boreids are derived from the Palaeozoic family Permochoristidae is, as pointed out by Grimaldi & Engel (2005), rather weakened by the point that permochoristids are known only from isolated wings, making it somewhat difficult to understand how they could be compared to boreids and a relationship suggested in the first place.

REFERENCES

Cooper, K. W. 1974. Sexual biology, chromosomes, development, life history and parasites of Boreus, especially of B. notoperates, a southern Californian Boreus. II. (Mecoptera, Boreidae). Psyche 81: 84-120.

Grimaldi, D., & M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press: New York.

Novokshonov, V. G. 2002. Order Panorpida Latreille, 1802. The scorpionflies (=Mecaptera Packard, 1886, =Mecoptera Comstock et Comstock, 1895, +Neomecoptera Hinton, 1958, +Paratrichoptera Tillyard, 1919, +Paramecoptera Tillyard, 1919). In History of Insects (A. P. Rasnitsyn & D. L. J. Quicke, eds.) pp. 194-199. Kluwer Academic Publishers: Dordrecht.