The larva of the Antlion fly digs conical pits to trap ants

This edited article about the ant-lion fly originally appeared in Look and Learn issue number 716 published on 4 October 1975.

The Antlion fly (left, second down)

The long insect with beautiful, delicately-veined wings fluttered down from the trees and settled on the sandy soil. It might have been mistaken for a dragon-fly, but it was in fact the, apparently strangely-named, ant-lion fly.

Selecting a dry, sheltered spot it laid a single egg in the sand. The white, oval egg had a sticky surface so that it immediately became coated with a layer of sand, making it quite invisible.

The little creature which eventually hatched from this egg had a plump, bristly, oval body and a small head from which sprouted a pair of formidable caliper-like jaws. It was only able to walk backwards.

This larva remained quiet for a short time then it buried its head in the sand and, with a sudden jerk, shot grains of sand forward and upwards to a distance of an inch (2.5 cm.). This action was repeated time after time until a circular pit was formed with the ant-lion larva buried at the bottom with just its jaws showing.

Soon an ant came hurrying by but, alas, too close to the ant-lion’s lair. The loose sand at the sides of the pit caused the ant to slide down the slope. As it tried to clamber back to the top the larva bombarded it with grains of sand and it fell back to the bottom of the pit where it was instantly gripped by the hollow, sickle-shaped mandibles. Thus the fierce little larva had its first meal. The dry skin of the unfortunate victim was then hurled as far as possible from the pit.

For the next two years or so the ant-lion larva stayed in its pit, remaining inactive during the winter months. Then it spun a silk cocoon for itself before changing into a pupa under the sand. Finally, in early summer, a perfect, winged insect emerged – the transformation was complete.

Ant-lions are found in many European countries, including France, but not in Britain.

Although ants are its principal diet, justifying its name, the ant-lion larva will make do with spiders, woodlice and other wingless insects unlucky enough to fall into its trap.