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Stick Insects

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I got my first stick insects back in the early sixties when I was in school. These were Carausius morosus, a species originally from India. See picture Their direct descendants are still alive and well. Many young specimens have found their way to children in the neighbourhood. In the Netherlands we have no indigenous species of Phasmids, but C. morosus is very common in terrariums. Different species are also available, especially when you are a member of the Dutch branch of the "Phasmid Study Group". I have two other species: Extatosoma tiaratum, a large stick from Queensland, Australia, See picture and Sipyloidea sipilus from Madagascar. See picture

Carausius morosus
C. morosus is a wing-less, rather slow moving species. It comes in two possible colours: brown and green. I think that this has nothing to do with genes, but with the level of moisture in their environment. This must be an adaptation to the changes between dry and wet seasons in India. All hatchlings start brown, but when there is sufficient fresh food, they turn green when they shed their first skin, and grow up to be green adults. This is of course a better camouflage during the daytime in the wet season, when they sit motionless, like a twig, between the fresh leaves of their food plants.
C. morosus is a parthenogenic species, meaning that the females reproduce without any assistance of the males. In fact, there are extremely few males around. In the years since 1963 when I started keeping C. morosus, I have seen only a few males, much thinner than the females. Probably there were more males millions of years ago, but this species has evolved in a way where sexual reproduction in the end has proved to be nonessential. From the eggs laid by the unfertilised females, healthy young are born, practically all of them females. Possibly some males develop when the eggs are kept at a temperature of 30 Centigrade during the first 30 days. I used to think that these males were a degeneration, a faint shadow of the original, that they did not know what to do when meeting a female and died soon. Now I have a male that is still alive after three months, and even displays an interest in the females, although I have not seen him copulate. C. morosus is (more or less) active during the night, and it moves away when the light is switched on, so possibly copulation does take place in the dark.

Sipyloidea sipilus
S. sipilus, a light brown species with pinkish wings, also reproduces in the unromantic but still very effective parthenogenic way. The young are fresh green until they reach their final, winged form. This species can move around rather quickly. When disturbed it often jumps from its leave or twig, just dropping to the ground or flying away. When cornered, it displays its wings and produces an unpleasant smell.

Extatosoma tiaratum
E. tiaratum does have males as well as females. I'd like to think that there is a certain amount of mutual affection between the sexes, but one can't be sure. The males are in any case very much attacted to the enormously fat adult females. These are up to 14 cm long, thorny all over, wing-less and they do not move around very much. When disturbed, they don't try to go away, but spread their thorny hind legs with which they strike out and squeeze your finger, at the same time producing a bad smell. They prefer to hang between the leaves that serve as food, convincingly looking like crumbled dead leaves. Their abdomen is usually bent backwards, almost touching the head. E. tiaratum's colour can be from khaki to brown, or green. In Australia, their food is Eucalyptus leaves, but I feed them bramble leaves all year round, and in summer leaves of various trees.
The males are up to 11 cm, much slimmer and more agile. As adults they have large wings and long antennae, probably for spotting the females. Sometimes two males can be seen very peacefully on the back of one female, I have never seen fights between males. The eggs hatch after nine or more months. The hatchlings are black, with a reddish head, and move quite fast when they run up from the ground into the trees. They resemble a large, vicious type of ant; another clever form of mimicry. After a few days, they lose their ant-like colours and their urge to run around, and become more like adults. Males and females can be distinguished after the first moult: the females are much thornier from then on.

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