Caulocampus

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Nematinae
Tribe: Nematini
Genus: Caulocampus Rohwer, 1912
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.

Caulocampus are small, about 3–5 mm in length (Prous et al. 2014). They are mostly black or yellow-brown; both species have yellow legs (Smith 1968).

Diversity

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

A key to species is included in Smith 1968.

Diagnostic characteristics

Subfamily characters​

Genus characters

May be confused with

Caulocampus may be confused with other genera in the subfamily Nematinae — particularly those with shorter antennae such as Adelomos or Hoplocampa — but can be distinguished by the space between fore wing veins M and Rs+M on vein R, the absence of vein 2r-rs, the length of the scape and pedicel, and the location of fore wing vein 2m-cu (Goulet 1992).

Exotic pest species of concern

none

Host associations

Caulocampus acericaulis feeds on Acer (maple) (Goulet 1992).

Life history

Females of C. acericaulis, the “maple petiole borer,” oviposit into the petioles of maple leaves. The larvae feed inside the petiole, hollowing out the vascular tissue. This feeding behavior causes the leaves to change color and prematurely fall off the tree, leaving behind a section of petiole with the larva still inside. At maturity, the larvae fall to the ground and burrow into the soil to overwinter and subsequently pupate. The species is univoltine (Smith 1968, Hale 2011).

Distribution

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

North America: Caulocampus occurs in the northeastern United States and southeastern Canada (Smith 1968).

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

Details about data used for maps can be found here.

Caulocampus acericaulis female lateral habitus; photo by J. Orr, WSDA

Caulocampus acericaulis female lateral habitus; photo by J. Orr, WSDA

Caulocampus acericaulis female dorsal habitus; photo by J. Orr, WSDA

Caulocampus acericaulis female dorsal habitus; photo by J. Orr, WSDA

Caulocampus acericaulis female face; photo by Q. Baine, WSDA

Caulocampus acericaulis female face; photo by Q. Baine, WSDA

Caulocampus acericaulis fore wing; photo by J. Orr, WSDA

Caulocampus acericaulis fore wing; photo by J. Orr, WSDA