Profenusa

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Heterarthrinae
Tribe: Fenusini
Genus: Profenusa MacGillivray, 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 Heterarthrinae subfamily are generally small and dark-colored. Many species of this family are economic pests of trees and shrubs and can be characterized by their skeletonizing or leaf-mining larval feeding behaviors. Heterarthrinae adults can be distinguished from those of other subfamilies by wing venation (Smith 1971a).

Profenusa are generally small, about 4 mm in length, and mostly black with whitish, yellow, or black legs (Smith 1971a). The Fenusini tribe are all leaf miners (Goulet 1992).

Diversity

There are 14 described extant species worldwide. Five species occur in North America (Taeger et al. 2010).

A key to Nearctic species is included in Smith 1971a.

Diagnostic characteristics

Subfamily characters

Genus characters​

May be confused with

Profenusa can be confused with other genera in the subfamily, especially similar genera Fenusa and Fenella. It can be distinguished by the number of antennal segments, small membranous area behind the first tergite, open cell R1 of the hind wing, and lack of a completely haired mesonotum (Goulet 1992).

Exotic pest species of concern

none

Native or introduced pest species

Profenusa canadensis is a pest on hawthorn, and in one case has caused defoliation of up to 50% on Prunus cerasus (English Morello cherry) trees (Hamilton 1950).

Profenusa thomsoni, commonly known as the amber-marked birch leafminer, is an introduced species that has become an established pest of birch trees. Infestations of this pest in Alaska in recent decades have resulted in thousands of damaged trees; one outbreak in 2002 resulted in defoliation of 25,000 acres of birch (Snyder et al. 2007). Since its introduction in the late 1990s, over 100,000 acres have been severely defoliated. In an assessment of invasive insect pests in Alaska, P. thomsoni was ranked very high due to its potential to create lasting ecological damage (Goldstein et al. 2005).

Host associations

Profenusa species in North America feed on Quercus alba (white oak), Quercus rubra (red oak), Quercus macrocarpa (bur oak), Quercus lobata (valley oak), Betula papyrifera (paper birch), Betula alleghaniensis (yellow birch), Betula populifolia (gray birch), Betula glandulosa, Betula nana, Betula occidentalis, Crataegus spp. (hawthorn), and Prunus spp. (cherry) (Smith 1971a).

Life history

Females oviposit single eggs into the upper surface of the leaf. After hatching, larvae feed on the inner leaf tissue and create blotch mines (Snyder et al. 2007). Larvae (except for P. canadensis) are characteristic in form: dorsoventrally flattened, undeveloped prolegs and reduced thoracic legs (Smith 1971a). At maturity, the larvae exit the mines and fall to the soil to build a cell, then burrow and overwinter. Profenusa are univoltine (Snyder et al. 2007). Males of P. alumna and P. thomsoni are unknown; these species may be parthenogenetic (Smith 1966b, Smith 1971a).

Distribution

World: This genus is known from North America, Europe, and Asia, including Siberia, China, and Japan (Digweed et al. 2009, Taeger et al. 2010).

North America: Profenusa has two distinct ranges in North America. Profenusa inspirata has a Pacific range with records in California, Nevada, and Oregon. Most species occur in the eastern United States and southeastern Canada, as far south as Virginia and west to Illinois (Smith 1971a). Profenusa thomsoni was introduced from Europe and was first collected in North America in Connecticut in the 1920s. The species is now established in Vermont, Maine, Quebec, Onatario, Manitoba, Alberta, Northern Territories, Yukon Territory, and Alaska (Digweed et al. 2009).

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

Details about data used for maps can be found here.

Profenusa thomsoni female lateral habitus; photo by J. Orr, WSDA

Profenusa thomsoni female lateral habitus; photo by J. Orr, WSDA

Profenusa alumna female lateral habitus; photo by J. Orr, WSDA

Profenusa alumna female lateral habitus; photo by J. Orr, WSDA

Profenusa thomsoni female dorsal habitus; photo by J. Orr, WSDA

Profenusa thomsoni female dorsal habitus; photo by J. Orr, WSDA

Profenusa alumna female face; photo by Q. Baine, WSDA

Profenusa alumna female face; photo by Q. Baine, WSDA

Profenusa inspirata male lateral habitus; photo by J. Orr, WSDA

Profenusa inspirata male lateral habitus; photo by J. Orr, WSDA

Profenusa inspirata male face; photo by Q. Baine, WSDA

Profenusa inspirata male face; photo by Q. Baine, WSDA

Profenusa alumna fore wing; photo by J. Orr, WSDA

Profenusa alumna fore wing; photo by J. Orr, WSDA