This weeks insect is Vanhornia eucnemidarum that belongs to the proctotrupoid family Vanhorniidae. The family contains one genus with three described species. Vanhoria eucnemidarum is the only Nearctic species of this rarely collected family. We were really surprised that the NCSU insect collection has five specimens and two are from Hill Forest near Durham!

In 1909 Crawford described the genus Vanhornia with one species, V. eucnemidarum, for which he erected the new family Vanhorniidae. The genus is named after R. W. Van Horn, who collected the type specimen.

Vanhorniids are easy to separate from other Proctotrupoidea based on their exodont mandible that is connected laterally by an extensive membrane to the head capsule, the presence of median furrow extending ventrally along the metasoma for accommodating the anteriorly oriented ovipositor and the presence of carapace. The carapace is a result of the fusion of the anterior metasomal segments. Although the exodont mandible and the presence of the carapace are shared with some ichneumonoid taxa, based on the wing venation and some other thoracic characters, vanhorniid wasps are real proctotrupoids.

The type specimens were reared from larval cells of an unidentified eucnemid beetle. Later the species has been reported as the parasitoid of Isorhipis ruficornis.

Vanhornia eucnemidarum specimens have been reared from dead maple trees.

Vanhornia eucnemidarum are found all over the Neartic Region.

Vanhornia eucnemidarum (Crawford 1909) species page at EOL: http://www.eol.org/pages/599953
Vanhornia eucnemidarum (Crawford 1909) species page at BugGuide: http://bugguide.net/node/view/16532
Brues, CT (1927) Observations on Wood-boring Insects, their Parasites and other Associated Insects.
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Castro, LR, Ruberu, K, Dowton, M(2006) Mitochondrial genomes of Vanhornia eucnemidarum (Apocrita: Vanhorniidae) and Primeuchroeus spp. (Aculeata: Chrysididae): evidence of rearranged mitochondrial genomes within the Apocrita (Insecta: Hymenoptera). Genome 2006. 49: 752–766.
Champlain, AB (1922) Records of Hymenopterous Parasites in Pennsylvania. Psyche 29: 95–100.
Crawford, JC (1909) A new family of parasitic Hymenoptera. Proceedings of the Entomological Society of Washington 11: 63–65.
Deyrup, M (1985) Notes on the Vanhorniidae (Hymenoptera). Great lakes Entomologist 18: 65–68.
He, J-H, and Chu, J-M (1990). A new genus and species of vanhorniidae from China (Hymenoptera: serphidae). Acta Entomologica Sinica 33: 102–104.
Mason, WRM (1983) The abdomen of Vanhornia eucnemidarum (Hymenoptera: Proctotrupoidea). Canadian Entomologist 116: 419–426.
Masner, L (1993) Superfamily Proctotrupoidea, Pp. 537–569 in Goulet, H and Huber, JT (eds). Hymenoptera of the world: An identification guide to families. Agriculture Canada Research Branch, Monograph 1894E. 668 pp.