Stick Insects

We’ve had some stick insects (Carausius morosus) at home for a while, and it’s easy to see why they are the favoured species for laboratory tests on insects (along with the American Cockroach Periplaneta americana) since they are so easy to breed and care for. To plan ahead after eggs at home starting hatching 4-5 months after laying, I brought a jar with 30 or so eggs to my office thinking they would take a similar time, and 1 month later I come into work every day to find another couple of new hatchlings to transfer to the nursery (another jar until they get larger). I guess the conditions are good, and the jars don’t get picked up and shaken by excited children!

This quick post is to start documenting their development, and to comment on observations about their gait patterns as part of my research on insect locomotion. At present the recent hatchlings have only exhibited the classic “tripod gait” (see movie below) where three legs, configured as a tripod, are moved synchronously, followed by the other three half a period later but the adults at home have shown other typical gaits as well as some interesting gaits in an unfortunate 5 legged adult (lost legs can be recovered during moulting at earlier stages of development or “instars”). I guess this is making me an experimental biologist!

Temporary home until they get a bit bigger

The photo below shows the size of the new hatchlings, a matter of a few millimeters (the 5p coin has a diameter of 18mm) whereas the adults grow to anywhere between 80 and 100mm. The egg is still considerably smaller than the hatchling, so it must be somewhat of a squeeze!

One day old insect, unhatched egg, and UK 5 pence coin.

As the saying goes in the film industry, never work with animals or children. The movie below took several attempts, and some editing, but clearly shows the insect using the tripod gait to move around. The coin and egg are also in view to show dimension.

Finally the only other decent photo I managed to get (still a bit blurred) as the subject dashed around the desk at a surprisingly brisk speed.

Another action shot!