Cabbage whiting (Pieris brassicae). Butterflies

Butterfly cabbage whale is quite large in size. The males reach 55 mm, the females are slightly larger - up to 60 mm in the span of the wings. Pieris brassicae L. is considered to be a malicious pest, destroying the crops of cultivated plants of the Cruciferous family and others. What methods exist for fighting these insects? Where do these butterflies live, how they look, how they evolve? About this and much more later in the article.

Generations

In the hot season and in the southern regions, as a rule, three generations develop, in the north - two. The first one leaves in the southern regions by the end of April and the beginning of May, in the northern by the end of May or the beginning of June. A larger second generation appears in July-August. The butterflies fly to the very end of September. The third generation in the southern areas can mix with the second. However, as a rule, individuals of the third age creep along the plant and live further apart from the others and can stay until October.

The cabbage whale development cycle

In the stage of the pupa, cabbage whiting overwinteres on tree trunks, bushes, fences, walls of buildings and other surfaces. After a short time after the flight, the individuals start laying eggs mainly on the underside of the cabbage leaves and other cultivated and weedy garden plants of the Cruciferae family. Eggs of a female stack in groups from fifteen to two hundred pieces in a heap. After six or thirteen days, caterpillars begin to appear. At first young people live together. Moult in the caterpillars occurs four times. The duration of the stage depends on the weather conditions. The cycle duration is within 13-38 days. Between the molts, an interval of three to seven days is maintained. Pupae become butterflies, on average, after 10-17 days. This new generation lays eggs by the end of July and beginning of August (in the middle lane). If the cultivation of crops is not carried out and the first individuals are struggling, then the following begin to grow and develop in large numbers. In the southern regions (in Central Asia), the pest has three or four, and in some areas (in Transcaucasia, for example) up to five generations.

Areal

Cabbage whiting is widely spread throughout the eastern European territory. Also representatives of the species can be found in the temperate zone of Asia, in the eastern regions to Japan, and also in North Africa. In 1993, penetration of individuals in the territory of the Southern Primorye was noted. Cabbage whiting was brought to Panama and Chile. In the regions located to the north of the Arctic Circle, it is possible to meet mainly migrant individuals. Favorite places of representatives of the species are roadsides, forest edges, parks, gardens, glades, forest belts along the railroad tracks. Also, cabbage is often found in settlements where there are cultivated cruciferous plants. It should, however, be said that the geographical distribution of the butterfly is limited by temperature conditions. Thus, wintering pupae at -20 degrees die in a rather large amount. The optimal temperature for growth of individuals is 20-26 degrees above zero. In too hot climates (more than 35-38 degrees), the development of cabbage whitewash slows down or it dies. The pest on the territory of Russia is very widespread, except, perhaps, the regions of Siberia and the Far North. There its presence and development is complicated by sufficiently low temperatures and severe climatic conditions.

Description

Cabbage whiting has wings of white color. The corners of the front are painted black, and on the back - a dark smear on the front edge of the surface. Females have distinctive features. In particular, on their front wings there are two round black spots. Eggs - yellow, have a bottle-shaped form. Their height is about 1.25 mm. Long ribs can be seen on the surface of the eggs. Gray-green sixteen-toned caterpillars have dark brown spots and points on the body, which are grouped into relatively even transverse rows. On the sides of the body and along the back pass yellow (on the back lighter than on the sides) stripes. The body of the caterpillar is covered with hairs and bristles. The head of the young specimens is black, and in adults it is covered with bright spots. The length of the caterpillar can reach up to 35-40 mm. The individuals of the first age are light green, and their body is covered with black warts. Pupa has an angular shape, greenish-yellow color, black dots on the sides and back.

Food

Cabbage whiting eats cruciferous plants. Young caterpillars, while being together for the first time, feed on the flesh from the bottom of the leaves, leaving the upper skin. Next, the individuals spread all over the plant. The cabbage begins to eat leaves mainly from the edges, adult caterpillars creep on the upper surface. They gnaw the flesh, leaving only coarse veins. Butterflies prefer to fly in the daytime. They feed (except for the flesh of the leaves) with plant nectar. Large concentrations of individuals can be found in areas protected from the wind and located near fences, tree plantations. In extensive areas, planted with cabbage, the pest is usually settled around the edges of the field.

Harm

Caterpillars cause damage to cabbage leaves, damaging radish, turnips, trout and other crops. They can also feed on plants of other families, for example, nasturtium, sirloin, capers. In addition, secretions from the glands of the body of the caterpillar cause irritation on the human body. Even individual cases of poisoning and death of birds feeding on these caterpillars have been recorded. The greatest harm cabbage whiting brings in the western and north-western regions of Russia.

Methods of pest control. Parasitizing insects

There are various ways to kill cabbage whitewash. In particular, one of the most effective are insect parasites. Of particular importance is the rider of the small fry, which lays eggs in the body of young caterpillars, sometimes up to one dozen in one individual. Larvae appear from eggs. They feed on the tissues of the body of caterpillars, leading them to death. Infected individuals first normally develop, but then become less mobile, acquiring a yellowish hue. After reaching a certain age, parasites begin to bore the body of the caterpillar, creeping out. Near the dying individual they begin to weave their cocoons, in which they pupate, and then turn into adult parasites. During the research it was established that the rider could hit up to 90% of the cabbage. In this regard, for effective control of the pest in the process of manual collection of caterpillars, it is necessary to leave cocoons of parasites for subsequent reproduction in the natural environment or to collect and transport them to the most populated caterpillar places.

other methods

Reproduction and development of the butterfly are largely prevented by various diseases. For example, the bacterial culture of wax moth is often used, which provokes the disease and the subsequent death of caterpillars. Particular importance among bacteriological pathologies is flasheria. Caterpillars affected by it cease to grow, become lemon yellow and quickly die. Inside, the tissues of the infected individual are transformed into gruel. In the eggs of the whitecoy, one of the trichogram (the egg-eating) can also appear.

One of the most simple methods of destroying a butterfly is a regular inspection of the lower surface of leaves of cruciferous plants, crushing of laid eggs. Manual collection of caterpillars and their destruction is used. In addition, today a lot of insecticides are produced . They are used to spray the future crop at the beginning of the season to prevent the appearance of pests, as well as their first occurrence to destroy young individuals. Plant treatment prevents further growth of caterpillars and protects the leaves of crops from damage.