Star sawfly weaver (Acantholyda posticalis = A.stellata, family Pamphiliidae - forest spider sawflies) - This is one of the most common pine needles pests on the territory of our country. Massive outbreaks of the star sawfly weaver are very dangerous, they can destroy plantings in large areas. Trees weakened by it are populated with stem pests.
Where it dwells and who it hurts
The star sawfly weaver lives in the pine forests of Europe, Siberia, Japan, and northern China. Its larvae feed on needles Scots pine, less often - Weymouth pine, rarely - Siberian pine.
Pine stands at the age of 10–40 years, both artificial and natural, suffer from this pest. Centers of mass reproduction occur periodically, approximately once every 10–15 years.
General view of 65-year-old pine plantations in the hearth of a star sawfly-weaver
Imagoes (males and females) fly in May – June. The beginning of the mass flight coincides with the beginning of dusting of male inflorescences of Scots pine and flowering of apple and lilac trees.
Female star sawfly weaver
The female is 11–16 mm long, the male is somewhat smaller - up to 13 mm. The body is flattened, black, with a variable yellowish-white pattern. The head is light below, black above with separate yellowish specks. Antennae are multi-segmented, long. The thorax and abdomen are black, with a variable pattern of yellowish-white spots. There are two pairs of wings, they are transparent, membranous, in a calm state, one above the other folds flat above the abdomen.
Eggs are laid singly, rarely 2–4 (rarely 8), on the surface of last year's needles, mainly in the well-lit part of the crown. Eggs are boat-shaped, pointed and raised at one pole, blunt at the other, up to 2.6 mm long, yellowish-green at first, later brownish.
Fecundity of females ranges from 15 to 50 eggs. After 8–18 days, larvae hatch, which in their development go through 5–6 instars. The larvae live one by one in cobweb tubes - caps woven among the needles on May shoots.
At first, the larvae eat up young needles, and later go down the branches and feed on last year's. In the last instars, the larvae leave the spider webs and live freely, braiding several branches with a thin web.
Larva up to 25 mm long and 2.5–2.8 mm wide. The head is brown, with dark brown specks on the top. Body coloration ranges from dirty green to marbled pink to dirty brown... In the middle of the body, on both sides, it runs along a strip of brown or purple. Above there are two intermittent stripes of the same color. Antennae, thoracic legs, and cerci brown.
Larvae that have gone into the soil with different color aberrations
The duration of development of larvae before leaving the soil is from 14 to 30 days.
Diapausing larvae without a cocoon (eonymph and partly pronymph) overwinter in earthen cradles in the upper soil layer at a depth of up to 10 cm (less often 40–60 cm). In young pine crops, cradles are located around the trunks within a radius of 20 cm, in older stands - within a radius of 1 m. Generation - from one to three years. With a one-year generation, overwintering larvae (eonymphs) turn into pronymphs in autumn or spring (have a pigmented pupal eye). In April – May, pronymphs turn into pupae. Pupal development depends on temperature and lasts from 6 to 24 days.
Damage to the star sawfly weaver
How to fight
Natural enemies of the star sawfly weaver: takhin flies, ktyri, predatory bugs, side walk spiders, lynx spiders, forest ants, ground beetles, grasshoppers, mice, shrews, hedgehogs, badgers, from birds - rooks, blackbirds, woodpeckers, crows, orioles, cuckoos, tits, starlings.