''Eriocampa ovata'', known generally as the alder sawfly or woolly alder sawfly, is a species of common sawfly in the family

Tenthredinidae Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foliage of trees and shrubs, with occasional exceptions that are leaf miners, stem ...

. The larvae feed on the leaves of the

common alder ''Alnus glutinosa'', the common alder, black alder, European alder, European black alder, or just alder, is a species of tree in the family Betulaceae, native to most of Europe, southwest Asia and northern Africa. It thrives in wet locations wh ...

(''Alnus glutinosa'') and the

grey alder ''Alnus incana'', the grey alder or speckled alder, is a species of multi-stemmed, shrubby tree in the birch family, with a wide range across the cooler parts of the Northern Hemisphere. Tolerant of wetter soils, it can slowly spread with runners ...

(''Alnus incana''), sometimes causing defoliation.

Description

The adult female is about long and mainly black, with the exception of the first two segments of the thorax, which are red, and the underside of the tips of the antennae, the inner side of the fore-tibia and the basal part of the hind femur, which are whitish. The head has numerous large puncture marks while the thorax has scattered smaller ones; the abdomen has faint transverse sculpturings. The wings are translucent with black veins. Adult males are unknown in North America, and rare in Europe, the females breeding by

parthenogenesis Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...

. The larvae grow to a length of . They are white, apart from a brown mark on the head, and are covered with a glossy, white woolly secretion produced by epidermal glands.

Distribution and habitat

The alder sawfly is native to Europe, but has been accidentally introduced into North America, both the Atlantic and Pacific coasts. It has spread to New York, Massachusetts, Quebec, Ontario, Washington, British Columbia, and Alaska.

Host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

trees include

(''Alnus glutinosa'') and

(''Alnus incana''), and in addition this sawfly has been recorded in Europe on

elm Elms are deciduous and semi-deciduous trees comprising the flowering plant genus ''Ulmus'' in the plant family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North ...

(''Ulmus'') and hazel (''Corylus'').

Life cycle

The adult female inserts her ovipositor into the upper surface of a leaf near the midrib to deposit her eggs. On hatching, the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e feed at first on the upper surface but later transfer to the underside. When fully developed they drop to the ground and make a cocoon in the

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent ...

in which they pupate and overwinter. In Quebec there are two generations per year, but in England there is just one. Eggs are laid in young foliage near the base of the tree with the upper crown usually unaffected. Leaves can be skeletonized with just the veins remaining, and growth of the tree may be reduced; stressed trees may be more susceptible to alder canker.

Gallery

File:Eriocampa ovata.jpg, Alder sawfly, ''Eriocampa ovata'' File:Eriocampa ovata (Woolly Alder Sawfly) larva, Arnhem, the Netherlands.jpg, Larva

Description

Distribution and habitat

Life cycle

Gallery

References

Further reading