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.
M. R. Shaw (Fri,) studied this question.