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| September 2004 |
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Meet SA's longest stick insect - almost the length of a 30cm rulerRob TomsNew Giant Stick Insect described from the Kruger Park and northern provinces of South Africa.
A case of mistaken identity has meant that for at least 100 years, South Africa's longest insect species, a giant stick insect remained unknown and unnamed. Thanks to an expert eye, a new giant stick insect, Bactrododema krugeri identified from museum specimens, has claimed its place in the so called Big 12 African Insects. Paul Brock describes this discovery in the Annals of the Transvaal Museum. With a body length of 163 mm or 295mm taking outstretched legs into account (males) and between 193mm and 226mm for females, this stick insect is the longest species in South Africa. It is also possibly the longest insect in the world described this millennium and could possibly be the longest described this millennium given that most of the largest insects in the world were already described in the last three centuries of the previous millennium. About 3000 stick insects are known worldwide and captivate because of their unique camouflage ability, often overlooked in gardens as being just sticks or twigs. However, a little torch-light at night reveals a hidden world as these nocturnal creatures move about feeding on plant matter. Leaf insects, so-called because they resemble broad leaves, are grouped in the same order as stick insects, Phasmida, however only about 30 species of the total 3000 are leaf insects. Giant stick insects are particularly interesting because of their size and weight and the fact that some of them can fly with their relatively small wings. The flight of these insects may be regarded as one of the wonders of aerodynamics, although often it is only a downward gliding flight. Stick insects generally move very slowly and the large ones tend to stay high up in trees. For this reason, they need to be good at conserving water, and need special blood or haemolymph to do this. Another interesting fact is that parthenogenesis is common in some genera and males are completely unknown in some species. Put simply, it means that females can lay viable eggs in the absence of a male. But why should such a large insect, Bactrododema krugeri have remained without a name for so long? Several specimens of this insect were collected and preserved in museums, but they looked so similar to other giant stick insects that it required an expert to recognize that this is a new species of stick insect. In fact a total of 13 males and 20 females are listed as paratypes (secondary examples included in the original description). The oldest specimen recorded was collected by Lord Gladstone in 1912 and since then has been collected several times in the Kruger Park and at other localities including Messina Nature Reserve, Pretoria and Botswana. Despite so many specimens, this stick insect remained undescribed until this year. Interestingly enough, another stick insect, Bactrododema tiaratum was first described in 1858 and was subsequently "re-described" six times before 1912 by different people using different names. These other names are now regarded as synonyms of Bactrododema tiaratum. If specimens of B. krugeri had been available to these authors they would almost certainly have described it. The Giant African Stick Insect Bactrododema tiaratum which can be found in Botswana, Namibia, South Africa, Swaziland and Zimbabwe is known to reach a length of 125-185mm in females (or up to 350mm. including legs stretched out). At 226mm, the newly described Bactrododema krugeri beats B. Tiaratum (now into third position) in the stakes for longest stick insect in South Africa as well as the previously described Bactricia bituberculata which reaches lengths of up to 200mm. The longest African stick insect is Bactrododema hippotaurum (263mm.) Although these insects are long, they are not heavy. One of the largest specimens in the Transvaal Museum has a dry weight of only 3,8g. Females of the bulky, broad-bodied Jungle Nymph Heteropteryx dilatata from Malaysia weigh up to 65g. in their egg-laying prime, one of the heaviest insects known. Although the African stick insects are by far the longest African insects and not far short of the Asian species, they are not amongst the heaviest stick insects. The largest known stick insect Phobaeticus kirbyi hails from Borneo. P.kirbyi is the longest insect in the world, the females of which reach 328mm (548mm including legs stretched out). A 278mm Malayan Phobaeticus serratipes for example measured 555mm including legs stretched out. The stick insects are one of the more popular insects kept as pets. However it is not easy to keep these insects in captivity, so it would be wise to do a little research, but better still, admire them from a distance out in nature. More information: By Rob Toms, Northern Flagship Institution, Transvaal Museum. Toms@nfi.co.za The author thanks Paul Brock for providing information. The longest insects in the world are stick insects (Order Phasmatodea) and this is one of the reasons that they are included in the BIG 12 African Insects http://www.nfi.org.za/inverts/BIG12/big12page.html The BIG 12 Insects are part of an exhibition called "Wonderful Things", currently on display at the Transvaal Museum Big 12 African Insects. http://www.nfi.org.za/inverts/BIG12/big12page.html
Brock, P.D. (2000). A complete guide to breeding stick and leaf insects. Kingdom
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