Birch bark beetle - the enemy of a birch grove

Sapwood (Scolutus) is a group of beetles from the subfamily of bark beetles, common in the Northern Hemisphere. It includes small insects 1.5-5 mm in size, specialized olifages. This means that beetles feed on only one plant and its related species. Sapwoods live in coniferous and deciduous forests. Birch bark beetle is a typical representative of the genus. Beetles and larvae damage the bark and gnaw the birch buds.

Morphological description of the species

Birch sapwood (Scolytus ratzeburgi) belongs to the subfamily of bark beetles, tribe sapwood. This is one of the largest representatives of its kind. The length of the imago is 4.5-6.5 mm. The compact head is pulled into the prothorax. The forehead is covered with longitudinal wrinkles, males have thick long hairs. Above the jaws a longitudinal keel. The eyes are oval, the front edge is notched. Antennae short, articulated, terminating in a flat mace, consisting of three segments.

Information. One of the manifestations of sexual dimorphism of a birch bark beetle is the shape of the forehead. In males it is flat, and in females it is convex.

The placum is large in relation to the body. The top is narrowed, the edges are rounded. The surface is covered with small dots. Flat elytra covered with longitudinal rows of point grooves. At the top are rounded off, this area is covered with hairs. The beetle is black and shiny. Wings are webbed, well developed. The abdomen is concave; its segments are directed obliquely upward. The female on the segments of the abdomen has rough puncture without tubercles. The male organ is distinguished by a large tubercle in the third segment. The outgrowth has the shape of a button. The limbs and antennae are brown.

Distribution area

The habitat of the birch bark beetle covers Western Europe, the Caucasus, Siberia, Transbaikalia. Extends to Mongolia. Beetles are found in Ukraine, in the Carpathians and Polesie.

Development features

The beetle years begin in May. Adults begin additional nutrition, eating the bark near the birch buds. Sapwoods settle on old and weakened trees, growing singly or in groups. Favorite places of the forest edge, roads, parks. Damage to the trunk is noted for characteristic symptoms:

• drying part of the crown;
• damage to the cortex in the form of round holes;
• the final stage is the death of the tree.

Round holes in the birch bark are located along the uterine passage. They are used as ventilation and marriage chambers.

Information. With an outbreak of mass reproduction, not only birch trees older than 50 years, but also young plantations are at risk.

The female forms a longitudinal uterine passage with a length of 13 cm, directed from the bottom up. Double moves in the form of a bracket are less common. laid by two females. Mating of insects occurs inside mating chambers. The ovipositor begins in June, the fertility of the female is 50-100 pieces. The eggs are small, translucent. The embryo develops in about two weeks. Hatching larvae make their own moves. They radiate from the fallopian tunnel. Offspring moves are clogged with drill flour. Due to their considerable length, they reach sapwood.

Information. Among the sapwoods, a communication system using chemical secretions is developed.

Crescent-shaped larva, off-white in color.The head capsule is highly sclerotized. Massive mandibles have teeth. The body is covered with pads for movement. there are small spines and bristles. Larvae winter in the moves. In the spring they pupate. The cradle of the pupa is located in the cortex. In May, young bugs gnaw a hole and fly out. One-year generation.

Harmful insects

Beetle larvae make moves in sapwood and cambium. Destruction of plant tissue leads to the death of the tree. When insects settle on one side of a young strong tree, there is a chance of birch conservation. Larval passages are overgrown with callus, and their inhabitants die. In addition to undermining the bark beetles during additional feeding, they carry dangerous infections, vascular and necrotic diseases.

Ways to fight

Supervision and sanitary rules, which include cutting down drying birches and sampling a dead forest, help to avoid infection of a large number of trees. Particular protection is required by urban and park plantations of birches, which are of value to cities. If a pest is detected, insecticides are treated. As forestry measures, laying out of hunting trees and sanding recently settled trunks and branches is recommended. Pests are caught using pheromone traps, and birds are attracted. The number of bark beetles is controlled by ground beetles, carapace, braconids, and nematodes.