Butterfly cabbage 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 for controlling 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 – early May, in the northern ones by the end of May – early June. The larger second generation appears in July-August. Butterflies fly until the end of September. The third generation in the southern regions can mix with the second. However, as a rule, individuals of the third age creep along the plant and live further apart from the rest and may linger until October.
The development cycle of cabbage whitewash
The pupa overwinter the pupa stage on tree trunks, shrubs, fences, walls of buildings and other surfaces. After a short period of time after departure, individuals begin to lay eggs mainly on the underside of cabbage leaves and other cultivated and weed garden plants of the Cruciferous family. Females lay eggs in groups of fifteen to two hundred pieces in a bunch. Six to thirteen days later, 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 between 13-38 days. In this case, an interval of three to seven days is maintained between molting. Pupae become butterflies, on average, after 10-17 days. This new generation lays eggs by the end of July and the 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 begin to grow and develop in mass quantity. In the southern regions (in Central Asia), the pest has three to four, and in some areas (in the Caucasus, for example) up to five generations.
Area
Cabbage white is widely distributed throughout the entire East European territory. 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 in the territory of Southern Primorye was noted. Cabbage was introduced to Panama and Chile. In areas located north of the Arctic Circle zone, you can mainly find migrant individuals. Favorite places of the species are roadsides, forest edges, parks, gardens, clearings, forest belts along the railway track. Cabbage is also 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 optimal temperature for the growth of individuals is considered to be 20-26 degrees above zero. In a too hot climate (more than 35-38 degrees), the development of cabbage whitewash slows down or it dies. A pest is very widespread throughout Russia, except, perhaps, for 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 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, two rounded black spots are located on their front wings. The eggs are yellow in color and have a bottle-shaped shape. Their height is about 1.25 mm. On the surface of the eggs, longitudinal ribs are visible. Gray-green sixteen-footed caterpillars have dark brown spots and dots on the body, which are grouped into relatively even transverse rows. On the sides of the body and along the back are yellow (on the back is lighter than on the sides) stripes. The body of the caterpillar is covered with hairs and bristles. The head of young individuals is black, and in adults it is covered with bright spots. The length of the caterpillar can reach up to 35-40 mm. Individuals of the first age are light green in color, and their body is covered with black warts. The pupa has an angular shape, a greenish-yellow color, black dots on the sides and back.
Food
Cabbage white eats cruciferous plants. Young caterpillars, being together for the first time, feed on the pulp from the bottom of the leaves, leaving the upper skin. Further, individuals spread throughout the plant. Cabbage leaves begin to eat leaves mainly from the edges, adult caterpillars crawl to the upper surface. They gnaw the flesh, leaving only coarse veins. Butterflies prefer to fly in the daytime. They feed (except for the pulp of leaves) on the nectar of plants. Large concentrations of individuals can be found in areas protected from the wind and located near fences, tree stands. On vast areas sown with cabbage, the pest, as a rule, settles at the edges of the field.
Harm
Caterpillars damage cabbage leaves, damage radishes, turnips, swede and other crops. They can also eat plants of other families, for example, nasturtium, rezeda, capers. In addition, the discharge from the glands of the body of the caterpillar provokes irritation on the human body. Even isolated cases of poisoning and death of birds feeding on these caterpillars were recorded. The greatest harm is caused by cabbage in the western and northwestern regions of Russia.
Pest control methods. Parasitic insects
There are various ways to destroy cabbage whitewash. In particular, one of the most effective are parasite 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. From the eggs appear larvae. They feed on the body tissues of the caterpillars, leading to their death. Infected individuals initially develop normally, but then become less mobile, acquiring a yellowish tint. Upon reaching a certain age, the parasites begin to drill 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 the cabbage. In this regard, for effective control of garden 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 transfer them to the places most populated by caterpillars.
other methods
The reproduction and development of butterflies is largely hindered by various diseases. For example, a bacterial culture of wax moth is often used, which provokes the disease and subsequent death of the caterpillars. Of particular importance among bacteriological pathologies is the flasheria. Caterpillars affected by it cease to grow, become lemon yellow and die quickly. Inside the tissue of the infected individual, they turn into gruel. One of the trichogramma (egg-eater) can also appear in the eggs of the whitewash.
One of the simplest methods of exterminating a butterfly is considered to be a regular inspection of the lower surface of the leaves of cruciferous plants, crushing laid eggs. Used manual collection of tracks and their destruction. In addition, quite a lot of insecticidal drugs are produced today . 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.