Winter scoop (northern locust, winter worm) - a nondescript gray butterfly, which in fact is a dangerous garden pest.
Its field of activity is quite wide: the
caterpillar of this insect can spoil up to 20 root crops of beets in just a day, and 12-14 specimens of crawling pests can cope with wheat per square meter. Corn, melons, rapeseed, tobacco, grapes, tree seedlings, sunflower and the main "weakness" - winter crops - is not a complete list of "taste preferences" of winter scoops.
Description of winter scoops
Externally, the winter scoop (photos are presented in the article), which belongs to the family of night nights, is noteworthy: the front wings are monotonous gray or yellowish-brown, with brown scales, have a clear pattern of wedge-shaped spots and transverse dark-light stripes, with a span of 30- 46 mm. Hind wings in females are grayish, in males white. The length of the body is 18-22 mm. The head and chest of the insect are covered with small hairs, there is a long strong proboscis and an eminence from the hairs on the forehead. Antennae: filiform - in females, comb - in males.
Habitat
The distribution area of winter scoops is all climatic regions, except for arid zones and the Far North. It is common for a pest to produce two generations, in the south side - three, in the north - one. At the stage of an adult caterpillar, a winter scoop inhabits areas of agricultural land, hibernates in the ground to a depth of 30 cm and is able to survive at a temperature of -11 ° C. With the onset of spring, when the soil warms up to + 10 ° C, insects migrate to the upper layer and pupate. A month is a period for the complete development of pupae, characterized by a reddish-brown color, 20 mm long and 2 spikes at the posterior end. The butterfly emerges from the pupa from the underside of the head part through a crack. Once free, the insect, under the pressure of blood in the veins, spreads its wings, which in less than half an hour become suitable for flight.
Periods of massive summer of butterflies in winter scoops
In mid-May (in the southern habitats - from the end of April), the years of the 1st generation butterflies begin, which lasts about three weeks, until about mid-July. From the middle of this month until the beginning of autumn, butterflies of the second generation fly en masse.
Summer activity of butterflies in winter scoops can be determined by installing light traps or troughs with fermenting molasses at a height of 20-25 cm from the ground (part of molasses + three parts of water + 50 grams per liter of water of previously fermented yeast). The average life span of a winter scoop butterfly is 5-25 days, the maximum value is 35-40 days.
The most active winter scoop, measures to combat which require an integrated approach, at night. Reinforced years are observed on calm nights, at temperatures from 12 to 15 ° C above zero.
During the day, a harmful insect hides under the foliage of weeds, piles of straw, lumps of soil and in other shelters. As an additional food, for optimal egg maturation, butterflies use flower nectar.
About the fertility of winter scoops
Oviposition is observed in the second half of August and occurs on vegetable crops, various flowering vegetation, weeds and fields that are reserved for winter crops. For this process, the winter scoop selects well-heated areas with low grass stand, planting of millet, corn, beets and other vegetable crops or a field with a loose soil structure.
Eggs are hemispherical in shape, white-dairy, radially ribbed, with a diameter of up to 0.9 mm. One female is able to lay up to 1000 eggs. The fertility of winter scoops depends on its nutrition. If flowering plants are absent, there is a massive death of butterflies. According to the experiment, females lived without food for up to 10 days and laid up to 44 eggs; when fed with floral syrup, life expectancy increased to 22 days, and the number of eggs laid - up to 860 pieces.
In regions with a dry climate, there have been cases of almost complete infertility of butterflies. The onset of favorable conditions contributes to the mass reproduction of winter scoops.
Caterpillar Winter Scoop
Caterpillars are born within 4-15 days and are characterized by a reddish head, fine-grained skin, distinct dark stripes on the sides, an earthy-gray body 40-50 mm long and eight pairs of legs (three pectoral, five abdominal).
First, they live under the rosettes of leaves or on their lower side and gnaw out small holes; do not touch the upper part. Also at this time, their main food are
weeds: sow thistle, quinoa, bindweed. Caterpillars by gnawing cause significant damage to seedlings of various crops, sown seeds of cotton, corn. It is in the period of the first and second age, until the damage to the plants has become global, it is recommended to carry out protective measures with chemical and biological agents.
The scale of the harm
At the third age, caterpillars are always in the upper soil layer and creep up only to satisfy hunger. During the night, such instances are able to destroy up to a dozen plants and feed on various vegetable crops, millet, sugar beets, cotton, melons, and maize. Now they already gnaw holes in the leaves, then completely eat the leaves, leaving only the center vein.
Caterpillars of the first generation cause harm in June-July, after which they plunge into the soil to a depth of 3-10 cm for pupation. The largest damage to agriculture is caused by second-generation caterpillars that damage the sown grain and the emergence of seedlings of winter cereals.
Winter scoop and measures to combat it
In order to reduce the number of winter scoops and reduce the damage caused by it, the soil must be carefully and timely treated, especially by directing activities to:
- global weed control - food for winter scoops;
- deep plowing, pre-sowing processing and cultivation of row-spacing, causing the destruction of most of the pupae and caterpillars of a harmful insect;
- irrigation in irrigated fields;
- early sowing of sunflower, sugar beet and other crops, reducing the harmfulness of the first generation of pests;
- coincidence of cultivation field work with the timing of mass egg laying;
- removal of flowering weeds along roadsides and near cultural plantings - this measure is aimed at a significant deterioration in the nutrition of the scoop.
The fight against winter scoops is effective when spraying plants with chemicals such as Fitoverm, Decis Extra, Agrovertin. You can fight winter scoop in a biological way: by issuing trichograms, which you want to carry out during the period of mass egg laying.