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Species Pristiphora geniculata - Mountain Ash Sawfly

Pristiphora geniculata Pristiphora geniculata Pristiphora geniculata Pristiphora geniculata Larvae eating Mt. Ash - Pristiphora geniculata Larvae eating Mt. Ash - Pristiphora geniculata Mountain Ash Sawfflies - Pristiphora geniculata first mountain ash sawflies in Oregon - Pristiphora geniculata
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 Tenthredinidae (Common Sawflies)
Subfamily Nematinae
Tribe Nematini (Willow Sawflies and allies)
Genus Pristiphora
Species geniculata (Mountain Ash Sawfly)
Explanation of Names
Pristiphora (Pristiphora) geniculata (Hartig 1840)
native to Europe, adventive in NA; widespread in ne. US & Canada; "common east of the Mississippi River"(1)

First detected in Washington State in 2009, and now common throughout the Puget Sound region
Main host: Mountain-ash (Sorbus)
Life Cycle
Overwinters as cocoon in the dirt. Two generations in the south, one in the north. First generation usually emerges in June and the second at the end of July.
Eggs are laid in slits cut around the edges of the leaflets and hatching occurs in 1 week. These larvae straddle the edge of the leaf and feed around the periphery. When disturbed they raise their abdomens in the form of an "S." Larvae of the 1st and 2nd instars are gregarious; the 4th and 5th instars feed singly. Feeding stops in 2-3 weeks and the larvae drop to the ground and spin cocoons in the duff and top soil. About 20% of these pupate and appear as 2nd generation adults in July.(2)
larva can cause extensive damage to leaves but rarely kills the host
earliest record in our area: NY 1926
Print References
Looney, C., Smith, D. R., Collman, S. J., Langor, D. W., & Peterson, M. A. (2016). Sawflies (Hymenoptera, Symphyta) newly recorded from Washington State. Journal of Hymenoptera Research, 49, 129.
Internet References
Works Cited
1.Garden Insects of North America : The Ultimate Guide to Backyard Bugs (Princeton Field Guides)
Whitney Cranshaw. 2004. Princeton University Press.
2.Eastern Forest Insects
Whiteford L. Baker. 1972. U.S. Department of Agriculture · Forest Service.
3.Pacific Northwest Nursery IPM Website
4.Forest invasive alien species (Canadian Forest Service)
5.Field guide to common insect pests of urban trees in the Northeast
Hanson T., Walker E. 2002. Waterbury, VT: Department of Forests, Parks and Recreation. 35 pp.
6.Maine Forest Service insect and disease fact sheets