''Acantholyda erythrocephala'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sawfly Sawflies are wasp-like insects that are in the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plant ...

in the family

Pamphiliidae Pamphiliidae (sometimes incorrectly spelled Pamphilidae) is a small family within Symphyta, containing some 200 species from the temperate regions of North America and Eurasia. The larvae feed on plants (often conifers), using silk to build webs o ...

commonly known as the red-headed pine sawfly or the pine false webworm."False" because "webworm" is commonly applied to various

moth Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...

larvae that form conspicuous webs. Native to Europe, it has been introduced into North America where it has become invasive.

Description

Fully-grown larvae of ''A. erythrocephala'' have yellowish heads spotted with dark brown, and greenish-grey bodies with purplish longitudinal stripes on the top and sides.

Distribution

The species is native to Europe and was introduced to North America in 1925, where it has become widespread in northern parts of the United States and Canada, where it is a major pest of

white pine ''Pinus'', the pines, is a genus of approximately 111 extant tree and shrub species. The genus is currently split into two subgenera: subgenus ''Pinus'' (hard pines), and subgenus ''Strobus'' (soft pines). Each of the subgenera have been further ...

(''Pinus strobus''). Other trees infested include

Scots pine ''Pinus sylvestris'', the Scots pine (UK), Scotch pine (US), Baltic pine, or European red pine is a species of tree in the pine family Pinaceae that is native to Eurasia. It can readily be identified by its combination of fairly short, blue-gr ...

(''Pinus sylvestris'') and

red pine ''Pinus resinosa'', known as red pine (also Norway pine in Minnesota), is a pine native to Eastern North America. Description Red pine is a coniferous evergreen tree characterized by tall, straight growth. It usually ranges from in heigh ...

(''Pinus resinosa'').

Life cycle

Adults emerge in late spring, and after mating, the female lays eggs on the previous year's needles. The eggs hatch in about two weeks and the larvae move to the base of the old needles and start to feed, only moving on to new needles if they exhaust the supply of old ones. The larvae construct silken webbing inside which they live in tubes, chewing off needles and pulling them inside the tubes for consumption; the tubes soon fill up with bits of needles, cast skins and

frass Frass refers loosely to the more or less solid excreta of insects, and to certain other related matter. Definition and etymology ''Frass'' is an informal term and accordingly it is variously used and variously defined. It is derived from the ...

. Older larvae construct their own individual tubes. By the end of June the larvae are fully developed and fall to the ground where they create earthen cells in which they spend the winter.

Ecology

In Europe, the larvae of ''Acantholyda erythrocephala'' are attacked by the

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

Tachinid fly ''

Myxexoristops hertingi ''Myxexoristops'' is a genus of flies in the family Tachinidae. Species *'' Myxexoristops abietis'' Herting, 1964 *'' Myxexoristops arctica'' (Zetterstedt, 1838) *'' Myxexoristops bicolor'' ( Villeneuve, 1908) *'' Myxexoristops blondeli'' ( Robi ...

''. In 2002, 2003 and 2004, in an effort to initiate a biological control programme in North America, pupae of this fly were imported from Italy and released in

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

in an area of

(''Pinus resinosa'') infested with sawfly larvae. Because populations of sawfly larvae have large natural swings, the impact of the parasitoid fly was difficult to evaluate. Another biocontrol measure investigated involved using an aqueous suspension of '' Neodiprion abietis'' '' nucleopolyhedravirus'' (NeabNPV); this reduced the survival rate of the sawfly larvae by about 50%, but its impact was again inconclusive. Defoliation by the sawfly larvae does not directly kill a tree, but it weakens it, allowing pathogens and pests such as bark beetles to attack, and these may result in mortality.

References

{{Taxonbar, from=Q14409602 Sawflies Sawflies described in 1758 Taxa named by Carl Linnaeus