Pest Type: Multi-Pest
Row: Lepidoptera – Lepidoptera
Family: Scoops – Noctuidae
It lives everywhere. In addition to cabbage plants, it damages field, vegetable, fruit and forest crops belonging to 30 families.
Butterfly with a wingspan of 40 – 50 mm; the fore wings are dark brown with a yellowish-white wavy line, in the middle of the wing forms two teeth facing outward in the form of the Latin letter “W”; two dark spots are located at the front edge, the kidney-shaped spot is bordered with white or partially white; hind wings gray, dark at margins. Egg size 0.6 – 0.7 mm, yellowish-white, with 32 – 38 radial ribs, of which 12 – 14 reach the micropylar zone.
The caterpillar is 35-50 mm long, sixteen-legged, changing color from grayish-brown to dark brown, almost black, with a wide yellow stripe on the sides of the body, and a dark herringbone pattern on the back. Pupa 19–24 mm in size, black-brown; two long outgrowths on the body, ending with a flattened mace.
Pupae winter in the soil, at a depth of 8 – 12 cm. Butterflies fly out in May. The beginning of the summer of butterflies coincides in time with the establishment of an average daily air temperature of 14 – 16 ° C and the sum of effective soil temperatures at a depth of 7 cm 189 – 196 ° C. Butterflies additionally feed on the nectar of flowers, usually weeds.
They fly in the evening and at night, and during the day they hide in secluded places. The duration of the flight of butterflies is 30 – 45 days, mass years are observed for 20 – 25 days. The female lays eggs in groups of 20 – 80 pieces, on the lower side of the leaves of various cultivated plants and weeds, often cabbage.
Fertility – from 600 to 2600 eggs. High temperatures and low humidity during the summer period of butterflies limit their fertility. Embryonic development lasts 6 to 12 days.
Caterpillars up to the second stage of development live in groups, skeletonize leaves from below, without affecting the epidermis of the upper side. Starting from the third stage of their development, they creep along with the plant and gnaw irregularly shaped holes in the leaves. They eat intensively at night and at dawn, and in the daytime, there is a decline in mobility and nutritional activity. Caterpillars of the middle and last stages often bite into the head of cabbage, in which they make moves and pollute it with their rare excrement. In cauliflower, caterpillars damage both flowers and inflorescences. The development of caterpillars lasts 25-30 days. On pupation migrate into the soil to a depth of 5 – 12 cm.
Part of the pest pupae in the event of insufficient soil moisture dies. To go through the full cycle of development of the cabbage scoop, the sum of effective temperatures of about 700 ° C is necessary. The second generation of butterflies occurs in the second half of July – in August. Caterpillars of the second generation develop over 30 – 40 days and damage the cabbage of medium and late varieties. Pupation of caterpillars occurs in late September.
Protective measures. Autumn plowing. Cultivation of row-spacing during the period of mass pupation of the first generation. Destruction of flowering weeds during the additional feeding of butterflies. Two trichogram releases of 40-50 thousand individuals per hectare against each generation of pest – at the beginning of egg-laying and 6-7 days after the first flight of butterflies. The use of biological products or insecticides is advisable when a shovel populates 5% of plants with an average density of two or more caterpillars per plant.