Notes on the biology of Carcina quercana (Fabricius) (Lepidoptera: Peleopodidae) and its parasitoids (Hymenoptera) in Germany and the Netherlands

Some puzzles concerning the life-history of Carcina quercana and its specialised parasitoid Venanides carcinae that were raised during a previous study (2018; 2019) in the Veluwe (Netherlands) (Shaw 2020) are resolved through a further study in the Harztor region of Thuringia (Germany) in 2024. Larvae are displaced from high positions in their host trees by storms, and re-establish on low sapling, seedling and epicormic growth. Factors allowing the host population to survive in the face of successive generations of V . carcinae attacking the single host generation include a proportion of the host generation reaching the safety of pupation before the first generation of adult V . carcinae has emerged, and probably extremely high levels of parasitism of (and associated hostfeeding on) V . carcinae cocoons. Vespid or bird predation of parasitoid cocoons at the end of the season may also be significant. It is concluded that C . quercana larvae present in mid-September in the Hogue Veluwe in July 2019 were most likely a result of exceptional drought conditions earlier in that year, and not indicative of a second generation, for which no evidence could be found in the Harztor population in 2024. The parasitoids reared are enumerated and their biology briefly described.