Pear fruit moth – Laspeyresia pyrivora

Pear fruit moth – Laspeyresia pyrivora

Butterfly with wingspan 17-22 mm; front wings of dark grey with light brown tint and distinct transverse stripe; the mirror is not clearly visible; lines fringing the mirror are ribbed-grey on the sides; hind wings are gray-brown. An egg is rounded, 1,3 mm in diameter, with the convex central part and flattened edges, freshly laid – dark red, later gray-red.

Caterpillar is 16-20 mm long, gray-white, translucent, with the brown head; abdominal legs with one-tier corollax with 11-17 blunt claws, anal – with 5-9 claws. Pupa 11-13 mm in size, dark brown; forehead with a conical protrusion, split at the top, spikes on segments of abdomen large, eight hooked bristles on the tip of the abdomen. Cocoon dark brown, dense.

Caterpillars that have finished feeding winter in cocoons in the soil at a depth of 5-10 cm and under fallen leaves. Pupation takes place 13-20 days after the blossoming of the pear variety Forest Beauty at the sum of effective temperatures (threshold 10 ° C) 172 ° C in the second – third decade of May. Pupation of individuals of the population is prolonged and lasts about a month. This elongation is also characteristic of the subsequent stages of pest development. The duration of pupal development is 19-22 days. Butterflies in the forest-steppe begin to fly in the second – third, in the Steppe – in the first – second decade of June, when the sum of effective temperatures reaches 370-400 ° C (at the threshold of development of 10 ° C). Mass years are observed 8-11 days after its beginning. In the garden of butterflies occur until the end of July. Their life expectancy is 9-14 days.

Butterflies are active from the beginning of the dusk until dark. Females lay one egg on pear fruits 4-6 days after departure. Fecundity of 40-80 eggs. Embryonic development lasts 6-10 days. The revival of caterpillars begins in the third decade of June when the sum of effective temperatures reaches 560 °С. Caterpillars gnaw at the lower shell of the egg and, not coming out to the surface, penetrate into the fetus, which makes a direct move to the seed chamber. The caterpillar eats all seeds, filling its covers with brown excrement. Several caterpillars can develop in one fruit. At the point where the caterpillar enters the fruit, the pressure is formed. Caterpillar develops 20-30 days. Leaving the fruit, it gnaws a straight path to the surface, which ends with a round hole diameter of 2-2.5 mm.

The exit wound is free of excreta. The most part of caterpillars leaves fruits which still hang on a tree, in the period with the second – third decade of July till the middle of August and passes to pupation. The generation is annual.

Damaged fruits fall off prematurely and decay. Early maturing pear varieties are the most severely damaged. Insufficient cold resistance causes a significant number of caterpillars to die in low snowy cold winters. Predators and parasites do not play a significant role in reducing the number of pear fruitworms. Caterpillars and pupae destroy many species of predators living in the surface layer of soil.

Protection measures: The most effective are agrotechnical methods and destruction of plant residues, autumn plowing of row-spanning rows and soil treatment in stem circles. Soil loosening in row-spacings and stem circles is especially effective during pouting of caterpillars in spring and pouting in summer. Taking into account that caterpillars do not move on fruits openly after regeneration, application of insecticides gives effect only if spraying is carried out before the beginning of mass laying of eggs – in about 35-40 days after the end of pear blossoming, when the sum of effective temperatures is 380-400 °С (at the threshold of 10 °С).

Leave a Reply

Your email address will not be published. Required fields are marked *

Solve : *
24 ⁄ 8 =