Fallocampus

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Nematinae
Tribe: Nematini
Genus: Fallocampus Wong, 1977
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).

Nematinae is the second-largest subfamily of Tenthredinidae, with over 1,250 species (Prous et al. 2014). They are most diverse in northern Eurasia and North America; only a few species occur in the Southern Hemisphere. Nematinae sawflies have a variety of feeding habits including external leaf feeding, leaf mining, and gall forming, and feed on a variety of hosts (Smith 2003b).

The Nematinae have been subject to numerous revisions in recent years. As of 2021, there are no comprehensive keys to many of the North American species of Nematinae (Prous et al. 2014). Because of changing taxonomy and extreme variability in morphology, identifying genera and species in the Nematinae may be more challenging than in other subfamilies of Tenthredindae. For this reason, knowing the host or behaviors of a specimen can be extremely helpful for identification within this subfamily.

Fallocampus are about 4–7 mm in length and mostly yellow in color, with variable black markings and clear wings (Smith 1976a).

Diversity

There are two described species worldwide, and they both occur in North America (Taeger et al. 2018).

A key to species of Fallocampus (as Platycampus) is included in Smith 1976a.

Diagnostic characteristics

Subfamily characters​

Genus characters

May be confused with

Fallocampus can be distinguished from other genera of Nematinae that have fore wing vein 2A+3A curved upwards by the absence of fore wing vein 2r-rs, the connection of vein 2m-cu to cell 1Rs, and the long inner tooth of the tarsal claw (Goulet 1992).

Exotic pest species of concern

none

Host associations

Fallocampus americanus feeds on Populus tremuloides (quaking aspen). Both that species and F. albostigmus may feed on other Populus species (Smith 1976c, Wong 1977).

Life history

Larvae have five instars and usually feed curled up on the underside of the leaf, creating small holes. At maturity, the larvae fall to the ground, build a cocoon in the soil, and overwinter (Wong 1977).

Distribution

World: The genus is known only from North America (Taeger et al. 2010).

North America: Fallocampus occurs in the northern United States and the Rocky Mountain regions south to New Mexico, and through much of Canada as far north as the Northwest Territories and Alaska (Smith 1976a).

Map data from the Smithsonian National Museum of Natural History Entomology Collection (USNM)

Details about data used for maps can be found here.

Fallocampus americanus female lateral habitus; photo by J. Orr, WSDA

Fallocampus americanus female lateral habitus; photo by J. Orr, WSDA

Fallocampus americanus female dorsal habitus; photo by J. Orr, WSDA

Fallocampus americanus female dorsal habitus; photo by J. Orr, WSDA

Fallocampus americanus female face; photo by Q. Baine, WSDA

Fallocampus americanus female face; photo by Q. Baine, WSDA

Fallocampus americanus male lateral habitus; photo by J. Orr, WSDA

Fallocampus americanus male lateral habitus; photo by J. Orr, WSDA

Fallocampus americanus male dorsal habitus; photo by J. Orr, WSDA

Fallocampus americanus male dorsal habitus; photo by J. Orr, WSDA

Fallocampus americanus fore wing; photo by J. Orr, WSDA

Fallocampus americanus fore wing; photo by J. Orr, WSDA