Eriocampa ovata

(Linnaeus, 1760)

alder sawfly, woolly alder sawfly

Eriocampa ovata is a in the , to Europe and to North America. Females reproduce primarily by ; males are unknown in North America and rare in Europe. The is notable for its distinctive woolly that feed on alder leaves.

Eriocampa ovata by (c) George Mitchell, some rights reserved (CC BY), uploaded by George Mitchell. Used under a CC-BY license.Eriocampa ovata by (c) Matt Bowser, some rights reserved (CC BY), uploaded by Matt Bowser. Used under a CC-BY license.Eriocampa ovata by Sandy Rae. Used under a CC BY-SA 3.0 license.

Pronunciation

How to pronounce Eriocampa ovata: /ˌɛrioʊˈkæmpə ˈoʊvətə/

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Identification

females distinguished by black body with red thoracic and specific pale markings on , , and . identified by woolly appearance, spot, and six or more pairs of . Distinguished from by proleg count; from other larvae by woolly secretion and association with alder.

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Habitat

Associated with alder trees (Alnus spp.) in riparian zones, wetlands, and urban forestry settings. feed on foliage; occurs in leaf litter on ground.

Distribution

to Europe; to North America. Recorded from Atlantic coast (New York, Massachusetts, Quebec, Ontario) and Pacific coast (Washington, British Columbia, Alaska). First published record in Manitoba, Canada in 2024.

Seasonality

In Quebec, two per year; in England, one generation per year. emerge in spring and summer; present during growing season. overwinter in leaf litter.

Diet

feed on leaves of common alder (Alnus glutinosa), grey alder (Alnus incana), and Manchurian alder (Alnus hirsuta 'Harbin'). In Europe, also recorded on elm (Ulmus) and hazel (Corylus).

Host Associations

  • Alnus glutinosa - larval common alder
  • Alnus incana - larval grey alder
  • Alnus hirsuta 'Harbin' - larval Prairie Horizon™ Manchurian alder; first published record 2024
  • Ulmus - larval Europe only
  • Corylus - larval Europe only

Life Cycle

Females insert into upper leaf surface near midrib to . feed first on upper leaf surface, later transfer to underside. Variable number of : 6 or 7; individuals with 7 instars have longer larval stages. Those destined to also have longer larval stages. Diapause more frequent in low humidity. As summer progresses, larval stage duration decreases while stage duration increases. Fully developed larvae drop to ground and construct cocoon in leaf litter to pupate and overwinter.

Behavior

Females reproduce by ; males absent in North America, rare in Europe. laid in young foliage near base of tree; upper crown usually unaffected. Larval feeding affects individual consumption: greatest leaf consumption per individual occurs at intermediate density (10 per leaf).

Ecological Role

Folivore on alder. Can cause , sometimes skeletonizing leaves with only remaining. Heavy may reduce tree growth; stressed trees may become more susceptible to alder canker.

Human Relevance

Minor pest of ornamental alder trees in urban forestry. can affect aesthetic value and tree health. on newly popular ornamental (Alnus hirsuta 'Harbin') highlights potential biosecurity considerations for material.

Similar Taxa

  • Eriocampa juglandisBoth produce woolly with waxy secretions, but E. juglandis feeds on walnut (Juglans) and butternut, not alder; larvae overwinter in soil as rather than in leaf litter.
  • Macremphytus tarsatusBoth are with waxy larval secretions, but M. tarsatus feeds on dogwood (Cornus) and has different larval coloration (, , and black when mature, not uniformly white).
  • Lepidoptera caterpillarsSimilar body form, but have six or more pairs of versus five or fewer in ; sawfly larvae lack (hooked ) on prolegs present in .

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