Family common name: argid sawflies
Genus: Aprosthema Konow, 1899
Argidae are found in all non-polar regions of the world (Smith and Middlekauff 1987, Smith 1992). They are external foliage feeders with a wide range of host plants. Additionally, the family exhibits some uncommon behaviors like the excretion of defensive compounds and subsocial habits (Smith 1992).
Aprosthema are rarely collected, and most species worldwide are described from a few or from a single specimen. They are recognized by characteristic 3-segmented antennae, which in males are distinctly forked (Smith 1971c, Vikberg 2004).
There are 57 described species restricted to the Northern Hemisphere. Species richness is relatively low in North America, with only two known species (Taeger et al. 2010).
A key to North American species of Aprosthema is included in Smith 1971c.
The family Argidae can be distinguished by the single-segmented flagellum of the antenna. The genus Aprosthema can be distinguished from other genera in the family by the lack of preapical spurs on the tibiae, simple tarsal claws, and a lack of vein Sc in the fore wing. Males are distinguished from related genera Arge and Atomacera by the conspicuous forked antennae (Smith 1992).
Larvae are external leaf feeders, and in North America feed on species of Fabaceae, including Acmispon grandifloras (chaparral bird’s-foot trefoil), Hosackia sp., and Lotus sp. (Smith 1992). Other leguminous hosts such as Vicia cracca (bird vetch) and Lathyrus vernus (spring vetchling) are recorded for European species of Aprosthema (Vikberg 2004).
Little is known about the biology of Aprosthema. In other genera of Argidae, the female oviposits along the margin of the leaf. After hatching, the larvae are external feeders on the foliage of plants (Smith 1989). Unlike other Argidae, larvae of the genera of the subfamily Sterictiphorinae are not known to live or pupate in aggregations (Smith 1992).
World: This genus ranges throughout Europe, east into China and Russia, and in North America (Taeger et al. 2010).
North America: Aprosthema is a western genus, with both North American species occurring in the Pacific Northwest (Washington, Oregon, California). Aprosthema brunniventre also occurs farther south into Nevada and Baja California Norte (Smith 1971c, Smith 1992, Taeger et al. 2010).
Map data from: GBIF.org (26 June 2019) GBIF Occurrence Download Aprosthema
Details about data used for maps can be found here.