How do Vanhorniidae (Hymenoptera) parasitize Eucnemidae (Coleoptera)?
The relationship between the beetle family Eucnemidae and the parasitic proctotrupoid family Vanhorniidae is discussed. The only proven host for Vanhornia eucnemidarum Crawford in North America is an undetermined species of the genus Isorhipis Boisduval and Lacordaire. In Europe, the only known host for Vanhornia leileri Hedqvist is Hylis cariniceps (Reitter). The biologies of the hosts differ radically and it appears unlikely that they could be parasitized in a typical proctotrupoid fashion in which eggs are placed in or on the host larva. This supports the hypothesis that small Vanhorniidae larvae attach themselves to the newly hatched beetle larvae, before they enter the wood on which they feed. The taxonomy of the genus Vanhornia Crawford is briefly discussed.