Gracillaria syringella (Formerly Caloptilia syringella)

The lilac leafminer is a European native that is now found throughout the Northeast and parts of eastern Canada. It was first reported in the United States around 1923. Adult moths are reported throughout the summer months. Moths are golden yellow in color and approximately 1/2 inch in length. Eggs are laid by females along the midrib or other veins on the undersides of host plant leaves. Eggs hatch and larvae enter the leaf directly beneath the egg shell. The initial mine they create is linear and cannot be seen from the top of the leaf. Larvae range in color from white to pale yellow to green. Second instar larvae are larger, and thus create larger mined areas that coalesce into a blotch shape. Sometimes the larvae breach each other's mines, in which case you can end up with several of them in a single mined area. The final instar larva will emerge from the mine, fold and skeletonize their leaf, and form a thin white cocoon within the fold. Lilac leafminers overwinter either as older larvae or pupae in dropped leaves. In the northernmost part of their range, the larvae will overwinter at the soil surface beneath the leaf litter. Several generations of this species may occur per year.