Several parasitic wasps help control the leafminer. Parasite activity is usually highest and easiest
to see following an outbreak of leafminers. The actual level of parasitization is highest, however, when
leafminer populations are low.
Female parasites usually lay their eggs in the leaf mine formed at the beginning of the tissue-feeding
stage. After hatching, parasitic larvae generally attach themselves to the outside of fourth- or fifth-instar
leafminers. The parasite grows rapidly and consumes the leafminer by its fifth instar. It then pupates
within the leaf mine, at about the same time as the leafminer would have. Although smaller than a leafminer
pupa, the parasite pupa can be distinguished by its larger head and eyes and flattened body. Following
pupation, the adult parasite cuts a hole in the leaf and emerges. Adult parasites are small but easy to
spot when populations are abundant because they fly in groups that hover near infested trees. Adult parasites
feed on the sap-feeding leafminers.
A leafminer parasite larva
pupa (bottom) and leafminer pupa