Caloptilia stigmatella, Family: Gracillariidae
Description: Caloptilia stigmatella is a micro-lepidoptera and a very unique insect in that it is both a leaf-miner and leaf-roller. The larva starts out as a leaf-miner and creates a blotch mine on the underside of the leaf near and directed toward the leaf edge. Once this is complete, the larva leaves the mine and makes a small leaf roll by tying the margin of a leaf to the underside of the leaf with silk. The larva is small (~3-4mm in length) and pale yellow. Since this miner is in the family Gracillariidae, they can be distinguished from other leaf rollers by looking at the prolegs. Gracillariidae caterpillars do not have a pair of prolegs on their 6th abdominal segment, while all other leaf rolling caterpillars typically will have this pair of prolegs. Once the larva is ready to pupate, it leaves the leaf roll and makes an oval silk cocoon on the underside of the leaf to pupate in. The small micro-lep adult emerges once metamorphosis is complete. The adult is brown or black and has a white triangle on both of the outer wings. This miner can easily be misidentified as the aspen leaf blotch miner (especially when the mine is still developing).
Biology: C. stigmatella feed on willows (Salix), poplars (Populus), and aspen (Populus).
Range: Common throughout North America and Europe (was likely introduced to North America from Europe)
Where they are found on aspen: Leaf edge mines can be found on the undersides of leaves throughout the canopy. The small leaf rolls can also be found throughout the canopy, but are typically spotted on newer leaves. The oval silk cocoons that they pupate in are also found on the undersides of leaves.
Helpful Resources:
Butterflies and Moths of North America
Wis(consin) Asp(en) Insect Communities 