The cabbage white butterfly is quite large in size. Males reach 55 mm, females are slightly larger - up to 60 mm in wingspan. Pieris brassicae L. is considered a malicious garden pest that destroys crops of cultivated plants of the Cruciferous family and others. What are the methods of dealing with these insects? Where do these butterflies live, how do they look, how do they develop? 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 leaves in the southern regions by the end of April-beginning of May, in the northern - by the end of May-beginning of June. A more numerous second generation appears in July-August. Butterflies fly until the very end of September. The third generation in the southern regions may mix with the second. However, as a rule, individuals of the third age creep through the plant and live further apart from the rest and may linger until October.
The development cycle of cabbage whites
The pupa stage is overwintered on tree trunks, shrubs, fences, building walls and other surfaces. After a short period of time after emergence, individuals beginlay eggs mainly on the underside of cabbage leaves and other cultivated and weed garden plants of the Cruciferous family. The eggs of the female are laid in groups of fifteen to two hundred pieces in a pile. After six to thirteen days, caterpillars begin to appear. At first, young individuals live together. Caterpillars molt four times. The duration of the stage depends on weather conditions. The duration of the cycle is in the range of 13-38 days. At the same time, an interval of three to seven days is maintained between molts. Pupae become butterflies, on average, after 10-17 days. This new generation lays eggs by the end of July-beginning of August (in the middle lane). If the processing of crops and the fight against the first individuals that have appeared are not carried out, then the following ones begin to grow and develop in mass quantities. 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.
Area
Cabbage white is widely distributed throughout Eastern Europe. Also, representatives of the species can be found in the temperate zone of Asia, in the eastern regions to Japan, as well as in North Africa. In 1993, the penetration of individuals into the territory of Southern Primorye was noted. The cabbage white has been introduced to Panama and Chile. In areas located north of the Arctic Circle zone, you can mainly meet migratory individuals. Favorite places of representatives of the species are roadsides, forest edges, parks, gardens, glades, forest belts alongrailroad track. Also, cabbage is often found in settlements where there are cultivated cruciferous plants. However, it should be said that the geographical distribution of the butterfly is limited by temperature conditions. So, wintering pupae at -20 degrees die in a fairly large number. The optimum temperature for the growth of individuals is considered to be 20-26 degrees above zero. In a climate that is too hot (more than 35-38 degrees), the development of cabbage whites slows down or it dies. The pest is very widespread on the territory of Russia, except, perhaps, the region of Siberia and the Far North. There, its presence and development is complicated by rather low temperatures and harsh climatic conditions.
Description
Cabbage white has white wings. The corners of the front ones are painted black, and the back ones have a dark stroke on the front edge of the surface. The females have distinctive features. In particular, there are two rounded black spots on their front wings. The eggs are yellow and bottle-shaped. Their height is about 1.25 mm. Longitudinal ribs are visible on the surface of the eggs. Gray-green sixteen-legged caterpillars have dark brown spots and dots on their bodies, which are grouped in relatively even transverse rows. On the sides of the body and along the back are yellow (lighter on the back than on the sides) stripes. The body of the caterpillar is covered with hairs and bristles. The head of juveniles is black, while in adults it is covered with light spots. The length of the caterpillar can reach up to 35-40 mm. Individuals of the first agelight green in color, and their body is covered with black warts. The pupa has an angular shape, greenish-yellow color, black dots on the sides and back.
Food
Cabbage whitefish eats cruciferous plants. Young caterpillars, being together for the first time, feed on the pulp from the lower part of the leaves, leaving the upper skin. Further, individuals spread throughout the plant. Cabbage begins to eat leaves mainly from the edges, adult caterpillars crawl to the upper surface. They gnaw at the flesh, leaving only coarse veins. Butterflies prefer to fly during the daytime. They feed (except for the pulp of leaves) with plant nectar. Large concentrations of individuals can be found in areas protected from the wind and located near fences and tree plantations. On vast areas sown with cabbage, the pest, as a rule, settles along the edges of the field.
Harm
Caterpillars damage cabbage leaves, damage radishes, turnips, swedes and other crops. They may also feed on plants of other families, such as nasturtium, mignonette, capers. In addition, secretions from the glands of the caterpillar's body provoke irritation on the human body. Even isolated cases of poisoning and death of birds that fed on these caterpillars have been recorded. The cabbage white causes the greatest harm in the western and northwestern regions of Russia.
Pest control methods. Parasitic insects
There are various ways to destroy cabbagewhites. In particular, one of the most effective are parasitic insects. Of particular importance is the small-bellied rider, which lays eggs in the body of young caterpillars, sometimes up to one dozen in one individual. The eggs hatch into larvae. They feed on the body tissues of caterpillars, leading them to death. Infected individuals develop normally at first, but then become less and less mobile, acquiring a yellowish tint. Upon reaching a certain age, the parasites begin to bore through the body of the caterpillar, crawling out. Near a dying individual, they begin to weave their cocoons, in which they pupate, and then turn into adult parasites. In the course of research, it was found that the rider could hit up to 90% of cabbage. In this regard, in order to effectively combat garden pests in the process of manual collection of caterpillars, it is necessary to leave cocoons of parasites for subsequent reproduction in the natural environment, or collect and transfer them to the places most populated by caterpillars.
Other ways
Reproduction and development of the butterfly is greatly hindered by various diseases. For example, a wax moth bacterial culture is often used, which provokes disease and subsequent death of caterpillars. Of particular importance among bacteriological pathologies is flacheria. Caterpillars affected by it stop growing, turn lemon yellow and quickly die. Inside the tissues of an infected individual turn into a pulp. One of the races of the Trichogramma (egg-eater) may also appear in the eggs of the whitefish.
One of the easiest methods to kill a butterflywhites is considered a regular inspection of the lower surface of the leaves of cruciferous plants, crushing laid eggs. Used manual collection of caterpillars and their destruction. In addition, today a lot of insecticidal preparations 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 at their first appearance to destroy young individuals. Plant treatment prevents further growth of caterpillars and protects crop leaves from damage.
