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Species Cimbex americanus - Elm Sawfly

large insect in my backyard-ID request - Cimbex americanus Wasp on tundra, Québec - Cimbex americanus Green Caterpillar  - Cimbex americanus Mating? - Cimbex americanus bee or wasp - Cimbex americanus Cimbex americana ? - Cimbex americanus Wasp? - Cimbex americanus Sawfly larva - Cimbex americanus
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon ("Symphyta" - Sawflies, Horntails, and Wood Wasps)
Family Cimbicidae (Cimbicid Sawflies)
Genus Cimbex
Species americanus (Elm Sawfly)
Synonyms and other taxonomic changes
Cimbex americanus Leach, 1817
= Cimbex americana [!] - Cimbex is masculine so a female epithet is in error (see iNaturalist and BugGuide discussions)
Explanation of Names
Cimbex americanus Leach, 1817
from the New Latin americānus ('American, of or related to the Americas')
adult 18-20 mm, larva up to 50 mm
The largest North American sawfly. Larvae yellowish-white with 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. Females commonly have a yellow banded abdomen.
most of NA (map)
adults May-Jun(1)
hosts include elm (Ulmus), maple (Acer), birch (Betula), willow (Salix), and basswood (Tilia); adults girdle bark on twigs
Life Cycle
Larvae have chemical defenses, ejecting fluids from glands near spiracles; often coil hind end around twigs; overwinter in cocoons, and pupate in spring
           Larva                          Pupa                      Adult male                Adult female                 Mating pair
not considered a forestry problem, but can defoliate shade/ornamental elms and willows (Forestry images)
Works Cited
1.National Audubon Society Field Guide to Insects and Spiders
Lorus and Margery Milne. 1980. Knopf.