Schizocerella

Taxonomy

Family: Argidae
Family common name: argid sawflies
Subfamily: Sterictiphorinae
Genus: Schizocerella Forsius, 1927
Subgenera: none

Background

Argidae is a family of typical sawflies that 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, this family exhibits some uncommon behaviors like the excretion of defensive compounds and subsocial habits (Smith 1992).

Schizocerella are small, about 4–6 mm in length, and in North America are generally orange and black in color. They are recognized by orange abdominal stripes and short, characteristic 3-segmented antennae, which in males are distinctly forked (Smith 1971c, Smith 1992, Vikberg 2004).

Diversity

There are five species described worldwide, all but one restricted to the Americas. Two species occur in North America (Smith 1992, Hartsough et al. 2007, Taeger et al. 2010).

Diagnostic characteristics

May be confused with

The family Argidae can be distinguished from other sawfies by the single-segmented flagellum of the antenna. The genus Schizocerella can be distinguished from other genera in the family by the orange and black stripes on the abdomen, short antennae, and its lack of a preapical spur. Males are distinguished from related genera Arge and Atomacera by the conspicuous forked antennae (Smith 1992).

Exotic pest species of concern

none

Host associations

Larvae in North America feed on Portulaca oleraceae and other Portulaca sp. (purslane), and less commonly on Claytonia perfoliata (miner’s lettuce) (Smith 1992, Hartsough et al. 2007).

Life history

The female oviposits into an incision she makes on the edge of a leaf. Up to four eggs are deposited in each leaf. After hatching, larvae feed on the foliage of the plant. The two North American species of Schizocerella feed on the same host and have overlapping ranges, but have distinctly different feeding strategies. S. pilicornis is a leaf-miner and S. lineata is an external defoliator. There are 5 larval instars. At maturity the prepupa drops to the ground, burrows into the top 5 cm of soil, then builds a cocoon of woven fibers and bits of soil. After pupation, the adult chews a small hole in the cocoon, then climbs out of the soil. Adults typically live 25–27 hours, during which time they mate and reproduce (Gorske et al. 1977).

Distribution

World: This genus ranges from as far north as Canada, as far south as Argentina. One species, S. pilicornis, has been introduced and is adventive in Australia (Smith 1971c, Smith 1992).

North America: Schizocerella occurs from southern Canada south through Central America (Hartsough et al. 2007).

Map data from: GBIF.org (26 June 2019) GBIF Occurrence Download Schizocerella

Details about data used for maps can be found here.

Schizoceralla pilicornis female lateral habitus; photo by J. Orr, WSDA

Schizoceralla pilicornis female lateral habitus; photo by J. Orr, WSDA

Schizocerella pilicornis female dorsal habitus; photo by J. Orr, WSDA

Schizocerella pilicornis female dorsal habitus; photo by J. Orr, WSDA

Schizocerella pilicornis female face; photo by J. Orr, WSDA

Schizocerella pilicornis female face; photo by J. Orr, WSDA

Schizocerella pilicornis male lateral habitus; photo by J. Orr, WSDA

Schizocerella pilicornis male lateral habitus; photo by J. Orr, WSDA

Schizocerella pilicornis male dorsal habitus; photo by J. Orr, WSDA

Schizocerella pilicornis male dorsal habitus; photo by J. Orr, WSDA

Schizocerella pilicornis male face; photo by J. Orr, WSDA

Schizocerella pilicornis male face; photo by J. Orr, WSDA

Schizocerella pilicornis fore wing; photo by J. Orr, WSDA

Schizocerella pilicornis fore wing; photo by J. Orr, WSDA