Krawchik Is A Polyphagous Parasite

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

Krawchik, or common kravchik, lives in the northern steppe of Russia, in the forest-steppe and in the southern part of woodland. Procuring food for their offspring, these pests damage a huge number of woody and cultivated plants, completely destroying leaves, buds, individual shoots and seedlings. Vineyards, as well as sunflower with corn, are especially affected by their destructive activity

Meet the pest

Crovchiks are weakly shiny black beetles ranging in size from 15 to 24 mm. Sometimes their bodies, especially from below, are characterized by a bluish tint, sometimes even with a barely perceptible copper sheen. The head of these parasites is rather large, equipped with strong and long upper jaws (and in males they have reddish processes below). The legs of the kravchiks are very strong, the abdomen is short, the anterior dorsum is transverse, undeveloped wings and short elytra fused at the seams. And their claws are somewhat reminiscent of knives.

The size of the eggs of these colorful beetles is 5 - 6 mm. They are usually oval and pale white in color. The laid eggs increase slightly in size, as they absorb moisture. White larvae up to 40 mm long, bent and thick. They are characterized by relatively small heads with very short antennae, as well as shortened conical legs. And the kravchik pupae are endowed with a large head bent towards the chest.

Krawchiks settle, as a rule, on the steppe slopes, in dry gullies, on untreated areas equipped with compacted soil, on road shoulders, in ravines and on railway embankments. The beetles overwinter at a depth of about half a meter. And in the spring, starting from the second decade of March and up to the first days of July, kravchiks get out on the soil surface. Their especially massive release is observed in the period from mid-April to mid-June. The released beetles begin to equip burrows, penetrating to a depth of fifteen to eighteen centimeters into the soil, at an angle of twenty-five to thirty degrees. They live in these burrows, and also hide at night and when any danger arises. The harmful beetles are especially active on sunny warm days.

Mating females and males equip joint minks, the average length of which is 18 - 27 cm, but in some cases it can reach seventy centimeters. Further, the females make chambers up to 30 cm in length, in the walls of which eggs are subsequently laid, wrapped in soil. On average, each female lays eight to eleven eggs (maximum twenty). The duration of the embryonic development of kravchiks is about 10 - 12 days. The harmful larvae emerging from the minks feed on the food prepared in advance by the parents, which they hide in the chambers. These larvae live for three weeks, having time to shed three times during this period, and at the end of the last molt they turn into pupae. Twelve or fourteen days later, beetles emerge from the pupae, remaining to winter in the chambers and leaving them only in the spring.

How to fight

Kravchik larvae can be affected by bacteriosis, and adult individuals are often destroyed by starlings and a number of other insectivorous birds.

To protect against kravchik, the plots are dug in with special fishing grooves (20-30 cm deep), and the edge strips of these plots are treated with insecticides (Decis, Diazinon, Arrivo, Karate, etc.). The outer walls of the grooves to be dug should be as even as possible so that the parasites that fall into them would not be able to get out. And as a bait, greens treated with pyrethroid preparations are placed on the bottom of the grooves. A valuable quality of pyrethroids is their harmlessness to pets and people - the effect of these drugs is directed exclusively to insects. Cravchiks are also collected by hand, which is greatly facilitated by the inability of these pests to fly.

Periodically, you need to loosen the soil - this is done in order to fill the entrance to the minks they have equipped with parasites.