Goliath beetle
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The goliath beetles are a number of species of beetles that belong to the taxonomic genus Goliathus. They are perhaps best known for being the largest insect in the world in terms of bulk, weight, and body mass. They can reach the length of 6 inches and can weigh up to 100 grams. With only just six known species in the world, they all reside in the tropical parts of Central Africa with the exception of the G. albosignatus who is native to the southern part of Africa.[1] The beetles come in many different colors such as brown, white, black, and orange.[2] They are fascinating insects in their own right.
Anatomy
The Goliath beetle is the largest insect in the world in terms of body mass. These monstrous sized creatures can grow up to 12 centimeters (4.72 inches) in length and weigh up to 115 grams (4 ounces). Like all beetles, the Goliath beetles possess a hard exoskeleton that covers their wings. This structure is called elytra. This protection benefits the beetle in many different situations. If the beetle is getting swarmed by prey it can blend in with the background and camouflage itself. This method can also be used in order to attract mates. Another useful method for this elytra is that some beetles are capable of trapping moisture on their wings and holding it inside this exoskeleton, which helps them survive many different environments. There are two parts to the elytra and one of those parts is used specifically for flying. [3] Males are easily identified since they have Y shaped horn on their head which they use as a weapon against other males. The females possess a bumpy shaped head which they use for burrowing into the ground when they lay their eggs. [4] Another characteristic that they share amongst their fellow species are their sharp claws called tarsi. The tarsi are located on the end of each of the beetle's six legs which helps them stay on tree trunks and branches. One of the noticeable features besides their monstrous size is their eye catching patterns on their body. All Goliath beetles possess a vertical line which is usually black, white, brown, or yellow. They have a keen sense of smell and excellent eye sight, thanks to its scent detectors which are located on their eyes and antennaes.[5]
Reproduction
After mating, Goliath beetles lay their eggs in the sandy soil. It will take the larvae a few months to mature, due to the huge size of the beetle. These larvae feed on higher protein food than other beetles. Mainly they eat leaves and wood. As larvae, they can weigh as much as a bottle of school glue(100 grams). They can be as long as much as 150mm(6 inches) in length. The larvae transforms into a pupa and it builds a structure around it that resembles a cocoon. This cocoon undergoes a change under the hard soil. While in the cocoon, the tissues of the beetle are solidified, and the adult beetle is formed. After this, the beetle goes into hibernation until the rainy season starts.[6] The beetle breaks open the cocoon soon after the rain begins. It searches for a mate and the cycle begins once again.[7] As an adult the Goliath beetle focuses mostly on feeding and reproduction. Once they have reproduce their life expectancy is quite short which is also true for many other insects. When locating a mate, Goliath beetles use pheromones to find their mate. The males fight over the female and defend their territories so only the largest and most capable males actually mate. During mating the female receives the male sperm which fertilizes the egg.[8]
Ecology
The Goliath beetles are mainly found in western equatorial Africa where the climate is tropical. They live in a warmer climate due to the fact that it is easier for them to breed. You can find Goliath beetles in the savannas and forests.[9] The Goliath beetle primarily feeds on fruits, sap, sweet foods, dung, dead plant matter, nectar and the pollen of plants. With their tarsi(sharp claws) they obtain the sap by penetrating stems and vines. Due to its massive size, the Goliath beetle is extremely strong and capable of carrying heavy objects that most other insects can't even lift. Despite its enormous size and weight, the beetles excel at both climbing and flying. When climbing in the top of the trees, they are quite active. They are diurnal, which means that they are active during the day.[10]Being the king of all insects, the Goliath beetle possesses few enemies which include large birds and venomous snakes.[11] Goliath beetles are also known as Mother Nature's Janitor. They are a huge benefit for us as humans since they eat dead plant materials and dung. If there were not any beetles that took care of the earth's garbage, it would be an extremely smelly world.[12]
Breeding and Rearing
During the last couple of years, the breeding of the Goliath beetle has become quite popular among many hobbyists who want to further investigate this mysterious creature. Even with great effort and patience, the beetles are particularly difficult to breed. In order to successfully breed them, the larva require a high protein diet, and the pupa needs specific environmental conditions to live. Before you let the females lay their eggs, you must have a container filled with a substrate composed of 60% rotted deciduous hardwood that is ground up, and 40% potting soil that is mixed together. The substrate must be moist but not very wet.[13] The containers that you place the substrate into should be two large identical storage boxes with open ends facing each other. Inside the containers, the depth of the substrate should be approximately 25-30cm with the bottom 8cm compacted by hand. On the top of the container you must open up at least two large holes(5cm X 2cm in size) for ventilation. On the surface of the substrate, thick flat pieces of bark should be placed in order to give the beetles a gripping surface, otherwise the beetles will flip over and get tired from trying to flip back into position. This can lead to the death of the insects. Another important note is that the males might be aggressive, so keep one male at a time in the box to avoid this problem. Sometimes the surrounding air inside the box can be very dry, so it is necessary to mist the top of the surface lightly. Most areas where Goliath beetles are found are in warm tropical climates, so to keep the same environment for the beetles they must be in the room with a temperature between 70-80 degrees Fahrenheit. For feeding, it is best to provide a sap flow feeder. You can make these by mixing 3 parts brown sugar and 1 part water and heating them up. Then let them cool down so the sap can be given to the beetles. Soak the sap onto cellulose sponges. When the beetles mate, they will start laying eggs within four weeks and the egg will be deposited at the bottom level of the substrate. The larvae will hatch out of the egg 12-14 days after being deposited.[14] When the larvae are present, it is recommended to move them to a different container when they are at least two weeks old. After two weeks, you must put the larvae in a separate container which allows them to grow more quickly. When it comes to feeding, it has been shown that the larvae will most readily accept pellets of soft moist cat or dog food. It is very important not to overfeed the larvae and replace the food every four days or else it can cause developmental problems.[15] In their new containers their should be several ventilation holes drilled in the lid. These containers can be small since the larvae only need enough to turn around inside them. As larvae grow, the container should become larger as well. When the larvae finish feeding they are fully grown they will form a pupa, similar to a caterpillar's cocoon. Construction of the outside shell takes at least several days to complete.[16] Place the pupa in well ventilated box with filled with substrate. The substrate should be allowed to dry almost completely. Then the beetle will slowly transform into an adult. Do not disturb it in any way. After five to six month take the pupae out wet the soil and re-bury them back in the box. The wetness will stimulate the adult beetles into coming out within a few days to a few weeks. They will live about one year in captivity which is longer than they would live in the wild.[17]
Gallery
Goliath Beetle
(G. goliathus)Goliath Beetle
(G. Orientalis)Goliath Beetle
(G. Orientalis)Goliath Beetle
(G. cacicuc)
References
- Goliathus The African Goliath Bettles Campbell's Natural Worlds,1998.
- It's Nature Let's Discover Goliath Beetle unknown author, It"s Nature, 2007
- The Goliath Beetle: The World's biggest insect Cyrus Dehkan, unknown publisher, October 17,2007.
- Goliath Beetle wiki unknown author, unknown publisher, accessed November 27 2010
- The Internet Encyclopedia of Science Goliath Beetle Liza Carruthers, The Worlds of David Darling, accessed 12-6-10