What is inside this folded, browned sugar maple leaf?

This is a Maple Trumpet Skeletonizer caterpillar’s home! This pale yellow caterpillar uses its frass (excrement) and silk to build a hideaway from predators. The tube grows wider as the caterpillar (and its frass) get larger, forming a trumpet-like shape. The trumpets are nestled into a leaf folded with silken threads. The caterpillars feed, and thus skeletonize, the leaf from the protection of the trumpet.

The Maple Trumpet Skeletonizer caterpillar out from the safety of their trumpet.

In the fall, the caterpillar drops to the ground, creates a silken cocoon between two leaves, and pupates. The brown and tan speckled moth emerges in June, mates, lays eggs singly on maple leaves, and the trumpet-building begins anew! 

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