Mountain Ash Sawfly
Pristiphora geniculata
This record describes Pristiphora geniculata (species). Recorded family: Tenthredinidae. Recorded order: Hymenoptera.
Identification and Appearance
Classification
- Kingdom
- Animalia
- Phylum
- Arthropoda
- Class
- Insecta
- Order
- Hymenoptera (Ants, Bees, Wasps and Sawflies)
- Family
- Tenthredinidae (Common Sawflies)
- Subfamily
- Nematinae
- Tribe
- Nematini
- Genus
- Pristiphora
Imported taxonomy record. Source availability varies; see the source references and editorial policy below.
Habitat and Range
Geographic Range
native to Europe, adventive in NA; widespread in ne.US & Canada; common east of the Mississippi River ; detected in WA in 2009, now common in the Puget Sound region
Diet and Behavior
Diet: Main host: Mountain-ash ( Sorbus )
Life History
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 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." Instars 1 & 2 gregarious; instars 4 & 5 feed singly. Feeding stops in 2‒3 weeks; 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.
Additional species information
Species notes from the sources
Etymology: Pristiphora geniculata (Hartig 1840)
About Flies: the wider group
Order-level background for Hymenoptera, the group containing Pristiphora geniculata. Species-specific details appear above.
Group overview
Hymenoptera includes over 150,000 described species of ants, bees, wasps, and sawflies. Earth harbors approximately 20 quadrillion (20×10^15) ants, with a combined biomass of ~12 megatons of dry carbon - exceeding the combined biomass of all wild birds and mammals (PNAS, 2022).
Ecological role of the group
About 35% of the world's food crops depend on animal pollinators. The chocolate industry, valued at over $100 billion, depends on pollinating flies and midges. Ants are the dominant soil engineers in most terrestrial ecosystems, turning more soil than earthworms in many habitats.
Economic and practical significance of the group
Pollinators contribute $235-577 billion worth of annual global food production (FAO). In the U.S., bee pollination alone benefits crops valued at $18 billion annually, and honey bees are responsible for $5.4 billion in agricultural productivity. Between April 2023-2024, 55.1% of managed honey bee colonies were lost. The U.S. bee population dropped from 5 million to 2.5 million.
Recorded sources for this group: FAO, USDA, EPA, PNAS (2022), US Fish & Wildlife Service. Imported estimates may describe particular regions or reporting periods.
Photos of Mountain Ash Sawfly (5)
Photo credits: Contributed by Lynette Elliott; Additional contributions by Beatriz Moisset , v belov , metrioptera , Marci Hess
Frequently Asked Questions About Mountain Ash Sawfly
Where is Mountain Ash Sawfly found?
Range: native to Europe, adventive in NA; widespread in ne.US & Canada; common east of the Mississippi River ; detected in WA in 2009, now common in the Puget Sound region
What does Mountain Ash Sawfly eat?
The diet of the Mountain Ash Sawfly includes Main host: Mountain-ash ( Sorbus ).
What is the life cycle of a Mountain Ash Sawfly?
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 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. Instars 1 & 2 gregarious; instars 4 & 5 feed singly. Feeding stops in 2‒3 weeks; 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.