Oviposition behavior and host records for the parasitic midge Trichochilus lacteipennis (Johannsen) (Chironomidae: Orthocladiinae)

Adult female Trichochilus lacteipennis were observed to extrude long strings of eggs (up to 15 cm) in flight over a lake in Maine, USA. Once extruded females dropped to the water surface and released the strings. Larvae of T. lacteipennis are parasitic on Elliptio complanata at this site and probably additional unionid mussel species elsewhere. Based on our dissections of parasitized mussels and previous reports, it appears T. lacteipennis spend all or nearly all of their larval life within their mussel host, with first instars initially free-living inside the mantle. At some point larvae enter the marsupium and complete larval development on a diet of mussel eggs and/or glochidia before pupating within the marsupium.