An unusual cause of death of a Stigmella-larva: a “pseudo-Bucculatrix” mine

Normally a mining larva doesn’t only eat the tissue right in front: it also eats with its head a bit to the side, causing the corridor to become wider than the larva itself. In some species the corridor may remain quite narrow, but it always widens sufficiently to make place for the growing larva.

The larva on this picture from the start on was unable the move its head sufficiently to the side to create the necessary space. It only can eat right in front. It has grown, but the corridor hasn’t widened. To accommodate the increase in volume the has lengthened unnaturally, giving it the aspect of a Bucculatrix larva. The similarity is enhanced by the small size of the mine. It will not become much larger: the larvae is doomed to be squeezed to death.

An investigation of the larva established it to be a Stigmella, and the combination of host plant and colour enabled a definite identification. It is difficult to tell if this is a rare phenomenon. I have seen it some times, but their small size makes the mines very inconspicuous.

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Ulmus minor, Duin en Kruidberg

mod 4.vii.2019