Species Cimbex americana - Elm sawfly

Tentrède de l'orme (French)

First described in 1817 by William Elford Leach as Cimbex americana

18-20 mm (adult), 25-50 mm (larva)

The elm sawfly is the largest North American sawfly with larvae reaching a length of almost two inches. Larvae are a yellowish-white color and possess a black dorsal stripe. While feeding, the larvae usually coil their posterior around a leaf or twig. At rest the larvae roll into a characteristic tight coil. The larvae spin tough, papery cocoons in the litter or just below the surface of the soil. Pink coloration is not common, most larvae are green to yellow in color.

Adult has glabrous thorax with white/yellow spot above, orange antennae.

Much of North America: Newfoundland south to North Carolina, west to Colorado, British Columbia, Alaska (1).

Woodlands

Late spring to early summer (May-June). Reported June (Minnesota, North Carolina mountains), May (North Carolina Piedmont).

Adults girdle bark on twigs.

Larval hosts include Elm (Ulmus), maple (Acer), birch(Betula), willow (Salix), and basswood (Tillia). Larvae have chemical defenses, ejecting fluids from glands near spiracles. Larva often coils hind end around twig. Larva overwinters in cocoon, pupates in spring.

From Forestry images: The elm sawfly is not considered a problem in forest situations, but can be a defoliator of shade and ornamental elm and willow trees.

Milne, p. 803--gives size, range (1)

Swan and Papp, pp. 516-517, fig. 1140

Cranshaw, pp. 84-85, photos of larvae (2)

Arnett, p. 542 (3)

Salsbury, p. 429--photo larva (4)

Brimley, p. 393 (5)

Forestry Images

North Carolina State University Entomology Collection    lists just C. americana for the state, with 6 pinned.

Insects of Cedar Creek   --Cimbex americana

University of Minnesota

Insects of Quebec

Zoological Miscellany, v.3, p.104    Leach's original description of the species (in Latin)