Читать книгу Extreme Insects - Richard Jones - Страница 19

NAME	violin beetles in the genus Mormolyce
LOCATION	Southeast Asia
ATTRIBUTE	most flattened insect form

Ground beetles (family Carabidae) are, as their name suggests, usually found running about on the ground, where they hunt small insects and other invertebrate prey. They are found throughout the world and are one of the most diverse and successful groups of insects. Their success is due in part to a peculiar structure near the base of each of their hind legs. The trochanter is a small muscle-filled lobe where the femur (thigh) joins the coxa (hip). It gives the long back legs extra strength, not just to push backwards, but to push downwards at the same time.

Ground beetles use this ability in a technique called wedge-pushing to squeeze into a tight space in the roots of grass or through the soil under a stone. First the beetle pushes its wedge-shaped body forwards as far as it can go, then it levers itself up and down to press back the herbage or soil slightly so it can push forwards again. Using this unique semi-subterranean propulsion method, ground beetles are able to pursue their prey farther and deeper into the dense thatch of plant roots and leaf litter.

The violin beetles – of which five species are known, all from Southeast Asia – have taken this squeezing habit to a bizarre conclusion. Rather than thrusting themselves through the undergrowth, they have chosen another, equally tight, spot in which to hunt: in the narrow crevices beneath the loose bark of dead trees, stumps and logs. As well as an extremely flattened body, violin beetles have a narrow head and thorax to examine minute cracks in the dead timber. They also explore cracks in the earth and the axils of bromeliads.