Malicious Spring Cabbage Fly

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Spring cabbage fly is a big lover of cabbage crops such as turnip, radish with radishes, cabbage, etc. You can meet it wherever these crops are grown. Damaging rutabagas, radish with radishes and other root crops, voracious larvae penetrate inside them, making numerous moves. The most harmful is the first generation of the spring cabbage fly, since the larvae of this generation damage seedlings and young vegetation. The growth of damaged crops slows down, their roots rot, and the leaves weaken, staining in blue-lead tones. Severely damaged plants often die

Meet the pest

Males of the spring cabbage fly reach 5 - 5.5 mm in size and are colored gray. On their abdomens one can notice one wide dark stripe, and on the front backs of the pests there are three dark stripes. On all segments of their bodies, there are also subtle transverse stripes. The abdomens of the parasites, narrowed at the tops, have a rounded final shape, and most of the head is assigned to their eyes.

Light gray females are always larger than males. They grow, as a rule, up to 6 - 6.5 mm. On each segment of their pointed abdomens there are wedge-shaped brownish specks, but the stripes on the chest of the pests are indistinct.

White cigar-shaped eggs reach a length of 1 - 1.5 mm and are equipped with small longitudinal grooves. Legless white larvae, growing up to 8 mm, are characterized by the absence of a pronounced head. The rear ends of their bodies are obliquely cut, and the front ends are slightly narrowed. A pair of convex spiracles, as well as fourteen conical tubercles, can be seen on the larva's body, and the four lower tubercles are paired together. The size of brownish oval false cocoons is 4 to 6 mm. On their posterior tips, fourteen conical tubercles characteristic of the larvae can also be seen.

Pupae overwinter in the soil in false cocoons, usually at a depth of ten to fifteen centimeters. Flies begin to fly out in April and May, as soon as the soil warms up to twelve to thirteen degrees. Often the time of their departure coincides with the beginning of planting cabbage seedlings in the ground. Additional food for flies is weed flowers.

Mating of gluttonous parasites occurs two or three days after their departure, and they begin to lay eggs after eight to ten days. Eggs are laid in small groups, in each of which there are no more than two to five of them. The main places of egg dislocation are soil cracks and soil lumps located near growing crops, as well as stalks near the root necks. The total fertility of female spring cabbage flies averages from one hundred to one and a half hundred eggs.

The key to the full-fledged embryonic development of pests is the absence of a sharp drop in temperature and increased air humidity. In dry and hot weather, the vast majority of laid eggs die. After five to ten days, larvae hatch, gnawing inside the main roots or eating them from the outside along with small roots. And after three molts, twenty to thirty days later, they pupate near the damaged vegetation in the soil. They do this in false cocoons.

The development of pupae takes from fifteen to twenty days in time. And the second generation flies are observed in June and July. As a rule, they concentrate on late cabbage varieties. The larvae of the second generation that have completed feeding go deeper into the soil, where they form puparia, in which they subsequently pupate and remain until the spring of next year. During the year, two generations of the spring cabbage fly develop, and in the southern regions there are three.

How to fight

Weed control and deep autumn plowing are effective preventive measures against the spring cabbage fly. The well-visible eggs of these parasites are periodically raked away from the stalks of plants - in this case, the hatched larvae die from exhaustion.

It makes sense to use insecticides at the summer stage of flies, as well as during the laying of eggs by them, when at least ten percent of the crops grown by garden enemies are inhabited. It will be advisable to use insecticides even when there are from three to five larvae or from five to six eggs per plant. The most commonly used chemicals are Aktara and Bazudin.

A good biological remedy against the spring cabbage fly is Nemabakt.

The spring cabbage fly also has natural enemies. The larvae and eggs of flies are destroyed by rove beetles, and their numbers are also limited by various predatory insects and even some types of fungi that infect both larvae and pupae in false cocoons.