Mosquito Attractants and Traps By William Quarles ‘The best way to control mosquitoes is to eliminate water sources that encourage breeding. A quick inspec- tion of the backyard might reveal dripping outdoor faucets, birdbaths, water gardens, watering cans, buck- ts, sauicers under potted plants, and other possible problems. Sources such as water gardens that cannot be emptied or drained can be stocked with mosquito fish or treated with the microbial insecticide Bacillus thuringiensis israelensis (BT) (sce Olkowski 2001), However, some mosquitoes escape the best source reduction and larval control programs to become irri- tating adults. Normally, an occasional mosquito bite is the cost of outdoor living, but the West Nile virus scare has driven individuals and government agencies to extremes (Quarles 2000} In some areas, pesticide foggers are being used. Foggers may give some immediate relief, but 99.9% of, the chemical never makes contact with a mosquito. ‘Mosquitoes usually just leave a treated area, then return when the residues decay. With more persistent pesticides, they develop resistance (Quarles 2001). More and more evidence Is accu mulating that areawide fogging has led to more human exposure than formerly thought. Researchers at, Mount Sinai in New York have just published a study on pesti- cides in the blood of pregnant women in New York City. Pyrethroid, metabolite levels, ‘were monitored from the summer of 1998 to the winter of 2001. Blood metabolite levels were highest in the summer of 2000, a time when New York City was being fogged for containment of the West Nile virus (Berkowitz et al. 2003). Since many people are reluctant to use pesticides, but are also fearful of West Nile virus, sales of mosquito traps and repellents have soared. When Common Sense Pest Control reviewed mosquito traps in 1996, few ‘options were available for the consumer market. Professionals had the CDC, New Jersey, and EVS traps. ‘These traps use light, and sometimes CO as attrac tants to monitor adult pest mosquito populations (Quarles 1996). (see Box A. History of Mosquito Traps) ‘At that time, the only option for the backyard was the zap trap—a light-baited electrocution trap that killed very few mosquitoes and eliminated many benefl- cial insects (Nascl et al. 1983; Frick and Tallamy 1996). Since then, mosquito traps have been vastly improved. A major advance is that most traps now use attractants that are targeted for mosquitoes and biting insects; beneficial insects are spared. Mosquito Host Seeking Behavior How effective are the attractants used in the new mosquito traps? Mosquitoes use a complex set of cues, Tong-range, midrange, and closerange to find a host. Most mosquitoes feed on sugary plant nectar or insect honeydew (Gillett 1972; Burkeit et al. 1999), but the females of many species need bloodmeals to produce cags (see Box B. Mosquito Biology). When not looking {or food, mosquitoes tstally rest on the underside of foliage and other discrete places. They are “activated” {nto flight when they receive host-recognition cues. Carbon dioxide is a mid to long-range cue. Humans emit about 250 ml of carbon dioxide a minute in breaths or pulses of about 12 per min. Concentration of CO in exhaled air is 4 to 5%, while the atmosphere averages about 0.03% to 0.04%. Carbon dioxide is car- ried on the wind, and attracts until concentrations are diluted by a factor of 100. When mosquitoes sense Cg, they fly slowly upwind toward the source Commercial mosquito traps emit from 350 to 500 ml of ‘Common Sense Pest Control XINt2) Spring 2008 ‘ox 7414, Berkeley, CA 94707COp per minute; the more COp, the greater the attrac tion (Kline and Mann 1998; Gillies 1980), Distance of attraction depends on the species, but traps should attract mosquitoes over a distance of at least 16 m (52.4 ft) (Clements 1963; 1999; Service 1993). Important pest species of the genera Culex, Aedes, and Anopheles can be caught in Cy baited traps. ‘Among these are Culex pipiens and Aedes vexans that vector West Nile fever. Mosquito species that have been caught by a combination of light and COg are shown in Table 1.(Service 1993) Host-Specific Cues Along with COg, other volatile cues from respiration drift downwind and allow a mosquito to identify a host from a distance. Fortunately, not all mosquitoes are looking for humans. Anopheles spp. mosquitoes prefer to attack humans and carry serious human pathogens. However, some Anopheles species prefer to attack other mammals, and attack humans only as a last resort (Taken 1991). Culex spp. generally prefer to attack birds, while Aedes spp. generally feed on mammals. These are just. general rules, as Culex nigripalpus prefers humans and Carries St. Louis encephalitis virus. Culex pipiens altacks birds, humans, and other mammals and car- ries West Nile virus from species to species (see Box D Mosquitoes and Disease). Since some mosquitoes bite both humans and other animals, attractants associated ‘with other species are often added as bait to backyard traps (Takken 1991). “Common Sense Pest Control NX) Spring 2008, "Box 7414, Berkeley, CA 94707Aedes aurifer Aedes atalanticus ‘Aedes communis Aedes solictans ‘Anopheles annulipes ‘Anopheles walker Culex australicus Culex pipiens Culex tarsalis Callseta morsitans Aedes abserratus Aedes bancroftan ‘Aedes exerucians ‘Aedes theobalds “Anopheles punctipennis Coguillettidia perturbans Culex fuscocephala Culex quinguefasciatus Culex vist Porophor ferox Table 1. Mosquitoes Caught with Light and Carbon Dioxide* ‘Aedes albifasciatus ‘aedes canadensis ‘Aedes punctor ‘Aedes trivittatus ‘Anopheles quadrimaculatus Culex inornata Culex giidus Culex stigmatosoma Culiseta ineidens Aedes alboannulatus Aedes cantator Culex annulirosteis Culex modestus ‘Culex tritaeniorhynchus Cow's Breath and Octenol One of these attractants was discovered during research on slecping sickness, which is carried by the tsetse fly, Glossina spp. The tsetse fly attacks cattle, and in some areas of Africa, cattle and flies cannot coexist. A volatile component of cow's breath, 1-octen- 3-01, hereafter referred to as octenol, is an attractant for tsetse fly and has been used in trapping programs for that insect. Since some mosquito species attack both cows and humans, USDA researchers in Florida decided to try combinations of octenol and carbon dioxide as attractants for pest mosquitoes (Kline et al 1990a). This research, reported in Box C, is the basis for the use of octenol in the new commercial traps. Mosquito Vision and Light Attraction As a mosquito gets closer to a host, it finally gets. {into visual range. If there is enough light to see a host, the mosquito swoops to attack. Mosquitoes are also attracted to light sources. The New Jersey, CDC and carly light traps made use of this attraction. Lights are part of the attraction of the MegaCatch and other new Commercial traps. Light intensity is often the most important environmental factor Influencing mosquito activity, and a number of different light sources have been tested, but the research has been rather limited (ervice 1993). For instance, a 15W fluorescent black light will catch 11 times as many biting midges, Cilltcoides vartipennis, as a 40W incandescent light, (Holbrook and Bobian 1989). Ultraviolet light is also attractive to Anopheles stephens (Wilton and Fay 1972), Unfortunately, black light also attracts many non-target species (Wieser-Schimpf et al. 1990; Wieser- Schimpf et al. 1991). Colored visible light has been tested. White inean- descent 3W bulbs are more attractive to biting midges, Chironomus salinarus, than eolored bulbs of the same wattage (All et al. 1994). However, colored LEDs are attractive to mosquitoes, and apparently cach mosquito species has its favorite color (Burkett et al. 1998). “Moonlight can be a factor in light trap performance. ‘Some mosquitoes are more active when the moon is full. For instance, Aedes taylort and Anopheles sinensis increase in numbers around human bails and bite more often during a full moon (Bidlingmayer 1964; Service 1993) Even though more mosquitoes are ying on a moonlight night, greater numbers are caught by light traps on a dark night. The important variable 4s light trap intensity above back- ground. The better mosquitoes are able to see a light trap, the more mos- guitoes are caught (Wilton 1975; Rubio-Palis 1992). Light traps are most effective for ‘mosquitoes that are active at night. Most Culex, Anopheles and Mansonia mosquitoes bite at night. Aedes tends to feed in the day or early evening. Psorophora and Haemagogus bite dur- ing the daytime (see Box B Mosquito Biology) (Service 1980: Service 1993). New Jersey trap Heat and Moisture As mosquitoes pass the visual threshold and draw closer to the visible target, they are attracted by heat and moisture (Kline and Lemire 1995). This attraction to heat and mofsture was reported in the lassie book by Gillett (1972). He used a container of hot water to draw mosquitoes away from his body. He observed Culex fatigans, “hovering around and even settling on warm dishes at mealtime” and “actually landing and probing warm pieces of toast with the pro- boscis.” Many of the new mosquito traps use heat and moisture as attractants. The Dragonily (see Resources) 4s designed to mimic the thermal outline of a small mammal, Skin Odor At close range, blood-seeking mosquitoes are drawn to humans and other mammals by a combination of odors from their skin and their breath, Human-seeking mosquitoes such as Aedes aegypti, Ae. albopictus and Anopheles albimanus are strongly attracted to human sweat. Armpit sweat is more attractive than sweat from other parts of the body. The components of human ‘Common Senge Pest Control XIX) Spring 2000 ‘Box 7414, Berkeley, CA 94707Box B. Biology of the Mosquito ‘The only area in the world where mosquitoes are absent is Anarctica. These ubiquitous, two-winged insects are part of the insect order Diptera and belong to the Culicidae family. There are 3 subfami- lies—Toxorhynchitinae, Anophelinae, and Cultcinae, Mosquitoes of the first subfamily are not generally pests, and their larvae actually eat pest mosquito larvae. The most important pest genera include Anopheles, Culex. Aedes, Mansonia, Haemagogus, ‘Sabethes and Psorophora. All mosquitoes go through complete metamorphosis including egg, larval, pupal and adult stages. ‘Adult mosquitoes are small, slender insects of, about 4 to 6 mm (1/4 in) length. Males have feathery antennae, those with short antennal hairs are females. An important mosquito characteristic is the long, slender proboscis that is used to penetrate skin. Males do not suck blood, females feed on blood in order to produce eggs. Unfed females are slender; those with blood meals have a red, swollen appear: ance; those carrying eggs have a swollen, whitish appearance. Females lay between 30 to 300 brown to blackish ‘eggs at one time. Anopheles eggs are boat or oval shape, and float on the water. Culex and some ‘Mansonia eggs are also laid on the water, but are deposited in the form of rafts. Eggs of these three ‘species cannot survive desiccation. Aedes, Psorophora and Haemagogus lay their eggs in damp places just beyond the water line. ‘Some Aedes prefer tree holes, clay pots and other containers. Aedes and Psorophora eggs can with- stand weeks or years of desiccation, and can survive cold weather. Hatching ts triggered by alternate cycles of flooding and drought, and not all the eggs hatch at the same time. These mosquitaes tend to be timed-release pests and never go away without good control measures. ‘Most mosquito larvae must come to the surface to breathe. They are most vulnerable at this time, and this is the reason that much mosquito control ‘work focuses on the larval stage. Anopheles larvae lie parallel to the water surface and breathe through the holes in their sides called spiracles. Culicine lar- vae hang from the surface at an angle and breath through a siphon tube. Many species spend 5-7 days in the larval stage. ‘Mosquitoes can develop anywhere there is stand- Ing water. The range of habitats is wide. Fresh water, salt water, brackish water, ground pools, wells, cesspools, marshes, containers, tires, tree holes, and aquatic vegetation are all areas where mosquitoes ‘can develop. Anopheles species generally prefer clean, unpolluted water. Many Aedes species develop in tree holes or containers. Culex tends to prefer pol- luted water associated with poor drainage and sani- Mosquito cass 2G “Anopheles spp. Aedes spp. and Culex spp. (Culex lays eggs in rafts, tation. Psorophora breeds in rice fields and marshy meadows. Mansonia mosquitoes are associated with aquatic vegetation. Haemagogus is a forest species in the U.S. (Service 1980). Feeding Habits Not all female mosquitoes feed on human blood. Toxorhynchitinae are all vegetarians. The two big. mosquito pest groups are the anophelines and the Culieines. Most pest mosquitoes are culicines that atlack whatever hosts are available, feeding on humans, other mammals, birds, and even reptiles. Many Culex prefer to feed on birds, but will feed on humans if necessary. Species that prefer to feed mainly on animals other than humans are called zoophilic. Anophelines usually prefer to feed on humans. Mosquito species with this preference are called anthropophilic Many Anopheles species prefer to bite inside houses. Aedes feeds outside, and tends to rest out- side before and after eating. Culex will feed either inside or outside Most Culex, Anopheles and Mansonia mosqultoes bite at night. Aedes tends to feed in the day of early evening. Psorophora and Haemagogus bite outside during the daytime. ‘Anopheles hunt, mate, bite and lay eggs at night. African anophelines tend to bite inside houses after 11 PM. South American anophelines tend to dine carlier than 9 PM, and tend to bite outside houses. When and what host any mosquito bites, though, depends on what is available. If few humans are available, anthropophilic species will temporarily become zoophile. ‘Switching of hosts has implications for human disease (sce Box D), Culex species are able to bring ‘encephalitis virus from birds to humans. Aedes species bring yellow fever virus from monkeys to humans. Since Anopheles conicentrates on humans, st will transmit at high frequency any human pathogen that itis able to incubate (Service 1980), ‘Common Sense Pest Control Xa) Spring 2008sweat that are attractive to mosquitoes are under investigation. Sweat contains amino acids, cholesterol, low molecular weight fatty acids, alcohol esters, and albumin. Some attractive compounds have been isolat- ed, but not identified. So far, lactic acid is the only human-assoclated pure chemical that attracts mosqui- toes in field tests. Even so, lactic acid must be com- bined with COg to be of any use in mosquito trapping and control (Service 1993; Takken 1991; Kline et al. 1990a). Chemical attraction can be quite specific. Field tests have shown that mosquitoes are able to discriminate between potential hosts. Some people are more attractive to mosquitoes than others, and the key to differential attraction is odor. This kind of gourmet activity is shown by mosquitoes such as Anopheles stephensi. Exactly why one person is more attractive than another is a rich topie of further research (Takken 1991). There is also an “invi- tational effect.” When mosquitoes bite, the feeding mos: quitoes apparently release volatile pheromones that attract yet more mosquitoes (Service 1993), None of the new traps make use of these short range cues, but these short range attractants are effective in traps. For instance, Kline (1998) found that the odor of dirty socks combined with a CO baited trap attracted larger numbers of mosquitoes than CO alone. The dirty socks were effective for 8 consecutive days! New Commercial Traps Most of the new traps use CO9 as an attractant. The C09 is usually generated by catalytic burning of propane, or itis released from a CO gas cylinder. In Some models, it fs generated chemically or photoc: alytically. Mosquito attractants other than CO include octenol, heat, moisture, lights, and even the sound of human heartbeats. Mosquitoes attracted to the traps are usually captured by fans that pull them either into anet, sticky trap, catch basin or electric grid. ‘The Mosquito Magnets, Lentek MKO1, Skeeter Vac, and Flowtron Power Trap generate COg from propane. ‘The Megacatch, Terminator, and the Dragonfly use CO gas cylinders. The advantage of propane is that heat and moisture are produced simul- taneously, and these are also mosquito attractants. Propane has the advantage of conven- ence and portability when these machines are used in remote areas. About 20 Ibs of propane generates 60 Ibs of COg and lasts about 3 weeks in continuous operation (Kline 2002}. For the case of the Mosquito Magnet Pro and the Skeeter Vac, a thermoelectric generator powers the fans, and no batteries or line current is needed. (See Table 2 Comparison of the New Traps) Mosquito Magnets and most of the others have a good reputation for safety. Coleman, however, produced a relatively inexpensive propane trap called the Mosquito Deleto that had to be recalled. The connee- tion between the propane tank and the trap was prone to leakage. The device has been redesigned and is cur- rently available (Coleman 2003). ‘The advantage of COg gas cylinders over propane is that releases of COg are easier to program. In the case of the Dragonfly, there are several release settings and trap operation is also controlled by a photocell. The MegaCatch releases COg in programmed pulses. Host- seeking mosquitoes react more strongly to pulses of COg that suggest respiration (Clements 1999), ‘Commun Sense Pest Control XIX) Spring 2003 ‘Bow 7414, Berkeley. CA 94707Table 2. Comparison of Mosquito Traps and Attractants Name | attractant | coz source __| Power | caten mode ___ Pricer Floweron eh, oct one 110 Ae fan, electrocution | 888 Inseetvoro ene one no ac fan, net 80 Black Hote beat, UY, C02. photocatainte | 110 AC fannet 800 Sobbtin C02, hest, moisture ‘methanol fame | thermociecrte | fan electrostatic id | 8195 Sone Web sound, est. octenal, UY one no ac fan, sticky tap 8109 Mosquito Dette 1602, heat octenol propane sone ste trp si00 Lentek Keo-Trap) (602, heat, moisture chemical earrdge | 110KC sucky trap S100 Mosquito Magnet Defender | CO2, heat, molsture,octenal propane cate | 110.AC fans, net e208 Flowtron Power Trap teat, moisture, C02 propane eatatic | 110.AC fan. chamber 5209 Lentek MO! (602, heat tg. moisture propane eatavie | 110.AC fan. net 8269 Mosquito Terminator | CO2, heat ght coz einaer — | 110.4C fan. net 5450 ‘Skeeter Vac (602, heat, ctenst Propane eatalyue | ahermocectric | fan. net 8495, Mosquito Magnet Liberty | CO2, heat, motstuse,oetenat Propane eatalyue | 110.4C fare, net 8495, Mepucatet pulsed 02, heat, programmed ights | CO2 cyinder | 110. AC fae, net wet catch | $590 Dragoally adjustable C02, heat, cctenot coreyiinder | 110.46, photocell Eetiated electrocution 9705 Mosquito Magnet Pro | 350 ml CO2, neat, moisture. octenot | propane catalytic | thermoelectric | fans. net 81295 ‘The price ofthese traps may vary according to distributor, Prices are sted nly to estimate costs, ‘Traps such as the Mosquito Magnet that collect mos- quitoes in nets are more useful for professionals because species identification is easier. Watching the net fill up may also be more rewarding to the backyard trapper. Glueboards and electric grids make identifica- tion and estimation of the numbers caught or destroyed more difficult Traps such as the Mosquito Magnet, Flowtron Zap, ‘Sonic Web, Skeeter Vac and the Dragonfly have octenol as an added attractant (see Box C). The Dragonfly releases more octenol than the other traps. ‘More exotic traps include the Sonic Web that emits human heatbeats, the Gobblin that is powered by methanol, and the Black Hole, that produces CO» by a photocatalytic process. The MegaCatch has a UV’ source and programmed flashing multicolored light, emitting diodes (LEDs). Mosquito Magnet The Mosquito Magnet made by American Biophysics, and the Dragonfly produced by BioSensory were the first of the new traps (see Resources). The Mosquito Magnets produce COy, water and heat by catalytically burning propane. Ocienol is added as an additional altractant, and mosquitoes that approach the trap are sucked into a net by vacuum fans, There are three models of the Mosquito Magnet. The more expensive Mosquito Magnet Pro produces its own electricity with a thermoelectric generator. The Liberty and Defender models use AC line current to power the fans, New models use counter flow geometry, which increases effectiveness (Kline 1999). One fan blows COy down- ward through a tube away from the trap, while another ‘more powerful fan produces a counter flow into the trap and net. Mosquitoes flying at less than 3.5 m/sec (11.5 fi/see) are swept into the trap (Kline 2002). Mosquito Magnets have gen- erally done well in comparison tests, Mosquito Magnets with counterflow geometry captured more mosquitoes in a tropical area of Korea than a number of other standard traps including the New Jersey and the CDC trap (Burkett et al. 2001; Burkett et al. 2002) Wheeler (2003) tested the Mosquito Magnet (Liberty), Mosquito Deleto and Sonic Web traps in areas of high mosquito density in the Cayman Islands. In 9 days the Mosquito Magnet caught about 7000 mosquitoes, the Mosquito Deleto caught 37 and the Sonic Web caught 5. About 60% captured were Culex, and about 30% Calicine mosquito and larvae ‘Common Sense Pest Control XDS2) Spring 2003 ‘ox 74 Berkeley, CA 98707Consumer Reports Consumer Reports (2003) tested the Mosquito Magnet (Liberty), the Lentek MKO1 and the Sonic Web, in closed room tests. Culex quingefasciatus and Aedes aegypti were released. About 75% of the mosquitoes were recaptured by the COg traps within 20 hours. The Sonic Web, which relies on heat, sound. and octenol, ‘caught only 25%. More of the Aedes aegypti, which Is an aggressive biter, were recovered than the Culex quin- quefasciatus. The testers found the Liberty was quieter and easier to use than the Lentek. MegaCatch “The MegaCatch uses programmed flashing lights from LEDs, carbon dioxide, heat, and vacuum fans as attractants. The carbon dioxide is released in pulses to ‘Throughout the world, mosquitoes vector arborvirus~ ¢s larthropod-borne viruses} such as yellow fever, encephalitis, and dengue. They also carty nematodes ‘and the malaria protozoa. Malaria, caused by ‘Plasmodium sp., is still one of the most serious diseases ‘n the world today. There are an estimated 300 to 500 ‘mullion eases worldwide, leading each year to 1.4 to 2.6 rilion deaths and much human misery. The malaria organism is resistant to treatment with drugs such as ‘quinine. Alternate drugs are more expensive and often have adverse effects. Malaria is carried by the Anopheles mosquito, and is primarily a problem in tropical countries. ‘About 80 million people in the world are infected ‘with lymphatic filariasis caused by the nematode, Wucheria bancroft. This disfiguring disease causes parts of the human body to grotesquely swell, a condi- tion called elephantiasis. This disease and the similar filariasis eaused by Brugia malay is carried by \ Anopheles. ‘Tn terms of numbers, dengue and dengue haemor- shagle fever are the most important arborviral diseases ‘worldwide. Dengue threatens nearly two-fifths of the ‘world’s population, ranging over 100 cotmtries infecting rllions and killing thousands each year in Aftica, the ‘Americas, Asia, the Pacific Islands and Eastern Europe, In many countries, itis the major cause of death among young children. Dengue is spread mainly by ‘Aedes aegypti and the tiger mosquito, Aedes albopictus. ‘Japanese encephalitis is mainly anAstant disease. ‘About 45,000 cases and 4,300 deaths were reported in 1990. Increased rice cultivation has eaused increased breeding of the vector, Culex tritaeniorhynchuus. Increased production of pigs has also increased the problem, as pigs act as alternate hosts, and amplify the virus. Unlike many mosquite-borne diseases: yellow fever: 4s on the decline. Yellow fever is carsied mainly by © Aedes spp. mosquitoes, especially Aedes aegypti. About 2,500 eases were reported in Africa int 1991, and only ~ 50-250 cases were seen in the Americas (WHO 1995). Disease in the U.S. ‘The principal malaria mosquito in the U.S. is “Anopheles quadrimaculatus, which is prevalent in the east and southeast. Anopheles freeborni is the western ‘malaria mosquito. Transmission rates are extremely low, and malaria is not a public health problem in the Box D, Mosquitoes and Disease U.S. (Swan and Papp 1976). However, malaria remains ‘a threat due to worldwide travel and immigration of + infected individuals from abroad. Yellow fever is no longer a problem in the U.S. Yellow fever in the U.S. is earried only by Aedes aegyptt. which can also carry dengue and encephalitis. This ‘mosquito is a serious pest of dogs as it carries the canine heartworm, Dtrofilaria tmmitis. (See Common. Sense Pest Control Quarterly 3(2):5-17.) ‘Since yellow fever and malaria aré no longer health problems in the U.S., encephalitis has become the most Important mosquito-vectored disease. There are cur- renily 5 different forms of encephalitis caused by 5 dif ferent viruses. Eastern equine encephalitis (EEE), ‘Western equine encephalitis (WEE), California encephalitis (CE) and Venenielan equine encephalitis (VEE), i ‘Of the five diseases, BEE is the most serious. Human mortality rates are 50-75%. WEE and SLE have fatalities of 5-20%. CE has fewer than 1% mortalit and VEK is a mild non-fatal disease in himans. ‘The common hotise mosquito ts Culléx pipiens, 118 primarily interested in birds and poultry, but also attacks humans and other mammals. It has caused at Jeast one epidemic of St: Louls encephalitis in the U.S. It also vectors the canine heartworm and filariasis in hhumans. A related species Culex tarsalis, is the prisil- pal vector of western equine encephalitis. Eastern: equine encephalitis is spread to man and horses by ‘Aedes species (Mulhern 1975). ‘The biting midge, Culicoides varipervis ts a common vector of buctongée virus in the U.S. (Holbrook and: Bobian 1980), West Nile Encephalitis peste Ei attacked New York City in: 1906 fee Quares 2000), Culex pipiens and Aad pone ce ee Sa ‘Since lange m ‘of birds were infected, the disease thas remained endemic, Sporadie outbreaks occur ies! ‘year. Of 20,000 people that get infected, 4000 will have symptoms. Mild symptoms inchide fever beadaché and ‘an occasional body rash. About 182 of the 20, develop eccephalis of severe symptoms, including off neck, high fever, tremors, muscle weakness, convul- sions or coma. The death rate is about 9 of each 20,000 Anfected or 6.8% of the severe cases (CDC 2003). ‘Common Sense Pest Contra XOX) Spring 2008 [Box 7414, Berkeley, CA 94707produce COg gradients fluctu- ating in time. Line current at 110 AC is used to power the machine. There are two catch modes: a dry mosquito net, and a wetcatch water tray. In cage studies, the MegaCatch with Cg caught about 73% of the female Aedes aegypti released within 24 hours. Without CO9, the trap caught about 52%. The wet catch mode captures ‘more biting midges than dry operation (Kline 2003), ‘Mosquito Magnet Liberty model Dragonfly ‘The Dragonfly takes up much less space than the other COy traps. It uses bottled COp with programmed releases. Photocell operation insures that CO is not wasted, but this feature reduces captures of daytime feeders. If daytime catches are desired, photocell opera- tion can be disabled, and the machine can be operated on a timer. The Dragonfly uses more octenol than the other traps. A wax matrix contains the octenol, which is slowly released as the wax is heated. Heat is pro- duced to fit the thermal profile of a small mammal, such as a rabbit. When mosquitoes try to land, they encounter an electrocution grid. Dragonfly prototypes have been used for mass trapping mosquitoes in Florida (Kline and Lemire 1998). Magnets and MegaCatch Kline (2003) compared the Mosquito Magnet, (Pro) and residential models with the Mega- Catch trap in laboratory ‘cages, in a suburban backyard, and in a Florida swamp. In these tests, the Mosquito Magnets were at a disad- vantage because Kline eliminated the octenol attractant. Under these conditions, the MegaCatch generally caught more mosquitoes. In competitive cage studies, the MegaCatch ‘caught about twice as New Jersey light trap many A. aegypti, as the Mosquito Magnet. The traps caught about the same numbers of Ochlerotatus (Aedes) taeniorhynchus or Culex quinquefasciatus. In a Florida backyard, the MegaCatch without CO» caught about the same number of mosquitoes as the Mosquito Magnet. When COy was added, the MegaCatch caught about 3x as many as the Magnet each night. In various ‘swamp tests, the MegaCatch caught from 2-24 times more mosquitoes. The Mosquito Magnet caught many more biting midges than the MegaCatch (Kline 2003). Other Florida Tests John Smith of Florida A&M University reported on comparison tests at the 2002 ESA Annual Meeting in Fort Lauderdale, FL. He compared seven commercial traps and one model under development in terms of numbers and species caught on a northwest Florida peninsula surrounded by a salt marsh. The MegaCatch and the Mosquito Magnet Liberty captured 2.5x to. almost 3x more mosquitoes than the next best trap, the Lentek MKO1 Mosquito Trap, and 4x to 6x more than. the Mosquito Deleto, Mosquito PowerTrap and the Dragonfly. The SonicWeb collected considerably fewer ‘mosquitoes than any of the other traps, which shows the importance of COg as an attractant. The Mosquito Magnet Liberty was able (o attract and capture 16 dif- ferent mosquito species, more than any of the other traps. Trap Placements ‘Trap placement is one of the keys to success with the new traps. If a COg baited trap is placed improper ly, it could make mosquito problems worse. Traps should be put 30-40 feet (9-12 m) away from porches or patios and other human congregation areas. If traps are placed too close, mosquitoes will see hosts and track them visually or thermally. Traps may also attract ticks, another reason to put them at a distance. Traps should be placed between mosquito breeding areas and areas where people will congregate. Mosquitoes should encounter the trap before they encounter hosts. Traps should be placed upwind from human activities, preferably in shady, open locations. Vegetation interferes with dispersal of trap C09 (ABC 20083). Are They Effective? Can mosqui- to traps baited with COy and ‘octenol Success: fully reduce backyard mos- quito popula- tions? Or better yet. can they ‘MegaCatch trap ‘Common Sense Best Control XIX) Spring 2003, Box 7414, Berkley, CA 94707reduce the number of bites? Mass trapping with attractants and traps has certainly been successful in some cases. USDA scientists D.L. Kline and D.R. Barnard were able to trap an estimated 90% of the pest salt marsh mosquitoes, Aedes taeniorhynchus, that plagued a 63-acre (25.5 ha) country club on Key Island at the northern end of the Florida Everglades. Kline and Barnard used mosquito traps baited with cylinders of COg and octenol. They used 52 traps set about 20 feet (6 m) apart, and traps were harvested every 30 days. After one intense 30-day period, more than 2 billion mosquitoes were collected—nearly 23 gallons (87 liters) of mosquitoes (Adams 1996; Kline and Lemire 1998). Dispensers of citronella or essential oils (Mosquito Incognito) (see Resources) that conceal human odors can be used where humans congregate to give added protection. Citronella candles might be tess useful, because mosquitoes are attracted to light and moisture, which might overcome the repellent effect of citronella oil. Traps and repellents could work together as part of an IPM program, Repellents would probably be effective longer, if the mosquito density was lowered by traps. ‘Traps would be more effective if hosts were disguised by repellents. Overzealous Advertising ‘These traps are great improvement over the Zap traps that were commercially available when Common Sense Pest Control Quarterly reviewed this field in 1996. ‘Traps with targeted attractants do not kill beneficial insects and can capture large numbers of mosquitoes. However, claims of removing all the mosquitoes from an. acre are probably exaggerated. ‘These claims result from measurement of COy dis- persal and extrapolations of cage capture tests. If CO can be detected 118 ft (86 m) away, and the wind keeps shifting in a 360 degree pattern, the COg gradient cov- fers an acre. If no mosquitoes are breeding, and the acre is covered with a cage, sooner or later all the mos- quitoes either die or find the trap. However, open space is not caged. Mosquitoes fly into and out of defined areas all the time. Dry weather suppresses breeding; wet weather and successful bloodmeals encourage it. Wind conditions determine movement, and only populations downwind from the trap are affected (Gillett 1972, Service 1993). Complex steady state kinetics develop between mosquito sources and the trap. The steady state equilibrium is complicat- ed by surges and crashes of breeding populations. Testimonials Cage tests and comparison field tests show that these traps can catch large numbers of mosquitoes. Other than cage tests and comparison field tests, the only information confirming efficacy of the new traps are the testimonials of consumers. Some of these testl- monials are on the American Biophysics website (ABC 2003). Many customers are happy with them, and itis ‘unlikely that the results in all these different situations are coincidence or a result of dry weather. Conclusion Published comparison tests show that CO traps catch more mosquitoes than those without CO. Mosquito Magnets and MegaCatch models generally have outperformed other traps in comparison tests. Many consumers are happy with the traps, and they should give relief in many situations. However, traps, should not be considered magic bullets that destroy all the biting mosquitoes by themselves. But, as one part of an IPM program including source reduction, larval control, and the judicious use of repellents, mosquito traps can help reduce dependence on sprays of toxic pesticides. References ABC (American Blophysies Corporation), 2003, Placement of taps. win. swore monqutmagnet com _Adanis, S. 1906. A high-tech mosque barr. Agricultural Research 44(9):12-14. ‘Ai, A. G. Cert, [, Basbato, G. Marchese, F. DDandrea and B. Stanley. 1994 Attraction of Chronos salnarus (Diptera: Chirenomidae) to rte Ught on at sland inthe saltwater Ingoon of Venice, aly J. Arm Mosq. 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Enlomal 96)301-308, ‘Common Sence Pest Control XIXE2) Spring 2008 Box 7414, Berkeley, CA 94707