Larch-sawfly
Guides
Bessa harveyi
Bessa harveyi is a tachinid fly parasitoid that attacks the larch sawfly, Pristiphora erichsonii, in North American larch forests. The species exhibits bivoltinism, with a partial second generation emerging in fall after host larvae have completed feeding; these fall-emerging adults rarely reproduce successfully due to scarcity of alternate hosts. Despite being a common parasite, it is ineffective at preventing or terminating outbreaks of its host. Population dynamics are strongly influenced by photoperiod and temperature, with warm, prolonged summers under long-day conditions increasing bivoltinism-related mortality.
Mesoleius tenthredinis
larch sawfly parasite
Mesoleius tenthredinis is a parasitoid ichneumonid wasp introduced from Europe to North America as a biological control agent against the larch sawfly (Pristiphora erichsonii). Its embryonic development has been studied in detail, revealing characteristics of primitive endoparasitoids. The species exhibits a notable host-parasite interaction involving encapsulation immunity in some host populations. A putative baculovirus has been detected in ovarian tissues of females.
Olesicampe benefactor
Olesicampe benefactor is a European ichneumonid wasp introduced to eastern North America as a biological control agent for the larch sawfly (Pristiphora erichsonii), a forest pest. Small numbers (147–388 individuals) were released in Maine, Nova Scotia, and New Brunswick in 1967. The species successfully established at multiple sites, surviving two to three winters at several locations. It disperses slowly, which may limit its effectiveness over large areas without multiple release points.