Winter Scoop (Scotia Segetum)

Pest Type: Multi-Pest

Row: Lepidoptera – Lepidoptera

Family: Scoops – Noctuidae

Winter scoop is widespread in Russia everywhere. Caterpillars are polyphagous, feed on plants from many botanical families. Butterfly size 40 – 50 mm. Fore wings brownish-gray (sometimes almost black), with three characteristic dark spots (kidney-shaped, round and wedge-shaped), bordered by a thin black line; the hind ones are white in the male and brownish-gray in the female.

An egg of 0.5 mm in size, ribbed (16 – 20 mm radius), with a flattened base; freshly deposited – milky white, subsequently darken.

Caterpillars of the first three stages – earthy-gray or grayish, dull, of the last stages – with a glossy cuticle, a dark narrow strip appears along the back; the abdominal legs are five pairs, the length of the caterpillar of the sixth stage is up to 52 mm; frontal sutures converge at the occipital foramen.

Pupa about 20 mm, black-brown, behind the back there are two points.

Wintering of the caterpillar of the sixth stage takes place at a depth of 10 – 25 cm. They can withstand the temperature drop to minus 11 ° C. The success of wintering depends on the development of fat cut. Younger caterpillars die at temperatures below minus 5 ° C. With the onset of increased spring temperatures, the caterpillars rise in the upper layers of the soil and pupate in oval earthen chambers at a depth of 5-6 cm. The development of pupae lasts 25 to 35 days. The years of butterflies in the south begin in mid-April, in the forest-steppe zone – in the third decade of May. The beginning of summer and its duration are determined by the meteorological conditions of the year. Butterflies are active at dusk and at night, during the day they hide under the leaves of weeds and in other shelters.

Their development requires additional nectar nutrition on flowering vegetation. Eggs are laid one at a time or in small groups on the underside of leaves and petioles of weeds, on dry plant debris, or on light, well-treated soil with sparse vegetation. On average, one female lays from 470 to 2200 eggs, which depends on the nutritional conditions of caterpillars and butterflies. In the beet-growing zone, butterflies of the first generation lay eggs on beets, corn, millet and vegetables, and the second generation – on fields prepared for planting winter crops that were not touched by their predecessors.

Embryonic development at an air temperature of 28 – 30 ° С lasts 2 – 5 days, and at 10 – 12 ° С – 24 days.

Caterpillars of the first generation appear in late May-early June. Depending on the air temperature, they develop 20-60 days. After feeding, the caterpillars in the soil at a depth of 1 – 6 cm turn into pronimphs, and after 2 – 10 days – into a pupa. After 11-14 days, second-generation butterflies fly out, whose years last about two months, eggs usually lay in August, and caterpillars appear at the end of the month. In total, the duration of the development of one generation is 50–70 days with the sum of effective temperatures 640–780 ° С.

In most of Russia, the winter scoop develops in two generations, and in the northern, and especially in the northwestern regions, in one.

The harmfulness of winter scoops is great. One first-generation caterpillar can destroy 10 to 15 sugar beet plants per night. Second-generation caterpillars damage winter crops more. Winterworm caterpillars can feed on at least 140 plant species from 36 families.

The reproduction of winter scoops is largely limited by parasites, predators, and diseases. In the eggs, caterpillars and pupae of the pest, more than 120 species of entomophagous develop, as well as viral diseases.

Of the birds, starlings, rooks, and jackdaws are the most energetic fighters of winter scoop caterpillars.

Protective measures. Of great importance in limiting the number of winters, scoops are the proper tillage for winter crops, as well as the cultivation of fields after unpaired predecessors; inter-row tillage on row crops; tillage after harvesting row-crop predecessors of winter crops leads to the death of caterpillars, prima and pupae.

From biological measures – the use of a double release of trichogram at the rate of 50 thousand individuals/ha; from chemical – treatment of winter wheat fields in the presence of two caterpillars 1.2 m permitted for use by insecticides.

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