Mechanisms of Pit Construction by Antlion Larvae1,2

Abstract

Observations of the construction of inverted conical pits by larvae of the antlion, Myemeleon immaculatus (De Geer), indicate that the role of physical factors may have been greatly underestimated. Although larvae must possess a mechanism for circling in order to trace the initial circular groove, they need not possess an intrinsic spiral orienting mechanism. As the larva circles and flicks sand along the bottom of a digging groove, the disproportionate collapse of material from the outer wall compared to that from the inner wall of the pit causes the digging groove to shift steadily inward. If the larva simply follows the bottom of this groove and continues to flick sand, an inverted conical pit will be formed.