Eutomostethus

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Blennocampinae
Tribe: Phymatocerini
Genus: Eutomostethus Enslin, 1914
Subgenera: none

Background

The Tenthredinidae are the most species-rich family and are found throughout the world, in all continents but Antarctica. They are known as the “common sawflies.” They can generally be recognized by a cylindrical body and long, segmented antennae. Otherwise, they come in a variety of colors, sizes, and forms (Goulet 1992).

Sawflies in the subfamily Blennocampinae have a diverse set of life histories and habits. Many species are restricted to subtropical and tropical regions, but the genus is still fairly species-rich in North America. Blennocampinae includes many sawflies that feed on ornamental and forestry crops. This subfamily can be recognized by wing venation and bidentate mandibles (Smith 1969d).

Eutomostethus is an introduced genus represented by two species in North America. Eutomostethus ephippium and E luteiventris are about 6–6.5 mm in length and mostly black with red and yellow markings and slightly darkened wings (Smith 1969d).

Diversity

There are 105 described extant species worldwide. Two species occur in North America (Taeger et al. 2010).

A key to Nearctic species is included in Smith 1969d.

Diagnostic characteristics

Subfamily characters

Genus characters

May be confused with

Eutomostethus can be confused with similar species in the subfamily Blennocampinae. It can be distinguished from most other genera by the length of the third antennal segment and from similar species Stethomostus by the simple fore tibial spur and the curved apex to veins 2A and 3A of fore wing (Smith 1969d, Goulet 1992).

Exotic pest species of concern

In China, E. longidentus is a destructive pest of Phyllostachys edulis (moso bamboo), causing severe defoliation (Maozhi et al. 1990, Hua et al. 2004). Eutomostethus reticulatus is also a moso bamboo pest in China that has adapted to and shares the two-year life cycle of the host (Chen et al. 2009).

Host associations

Eutomostethus ephippium feeds on Poaceae species, including species of Poa (meadow grasses). Eutomostethus luteiventris feeds on species of Juncus (rushes) (Smith 1969d, Macek 2014).

Life history

The specific biology in North America is not documented. In England, E. luteiventris larvae burrow into the stems of rushes, where they feed for the early part of their development. In the last instar, the larvae emerge and feed on the leaves externally (Smith 1969d).

Distribution

World: This genus is known from North America, throughout Europe and East Asia, and in North Africa and India (Smith 1969d, Goulet 1992, Saini et al. 2005, Taeger et al. 2018).

North America: Eutomostethus was introduced and now both introduced species have two distinct North American ranges, one in the northeastern United States and southeastern Canada, and one in the northern West Coast, from California to British Columbia and Alberta (Smith 1969d).

Map data from: GBIF.org (29 October 2019) GBIF Occurrence Download Eutomostethus

Details about data used for maps can be found here.

Eutomosthethus luteiventris female lateral habitus; photo by J. Orr, WSDA

Eutomosthethus luteiventris female lateral habitus; photo by J. Orr, WSDA

Eutomostethus luteiventris female dorsal habitus; photo by Q. Baine, WSDA

Eutomostethus luteiventris female dorsal habitus; photo by Q. Baine, WSDA

Eutomostethus luteiventris female face; photo by Q. Baine, WSDA

Eutomostethus luteiventris female face; photo by Q. Baine, WSDA

Eutomostethus luteiventris wings; photo by P. Jones, WSDA

Eutomostethus luteiventris wings; photo by P. Jones, WSDA