Colorado Beetle - Leptinotarsa decemlineata Say.
It is called the scourge of potato fields. The native land of this leaf beetle is North America, where it has long inhabited, feeding on local weeds. Later, when colonists began to cultivate potatoes in large quantities, the beetle switched to feeding on the leaves of potato plants. The abundance of food inevitably affected the increase in the reproduction of this beetle. Its harmfulness was first noted in the state of Colorado, from which the beetle got its modern name. Thus, it turned into one of the most dangerous agricultural pests. Soon, the beetle spread to most states in the USA and the southern part of Canada. At the end of World War I, Americans brought this pest to France, from where it quickly spread throughout Europe and moved further east.
The appearance of the Colorado beetle is very characteristic. The body is oval, strongly convex, and shiny. The beetle is yellow or red-yellow, less commonly yellow-brown. The elytra are lighter, with ten black stripes. There are dark spots on the head and pronotum. The body is short-oval and convex. The body length is 8–12 mm, width is 6–7 mm. The antennae are twelve-segmented, gradually thickening towards the tip. The first six segments of the antennae are yellow, the rest are black. The legs are black, equipped with long, grasping claws.
The egg is red-yellow, shiny, and elongated-oval. Length is 0.8–1.4 mm.
The younger larva is dark gray, the older one is red-yellow (brick-colored). The body is fleshy, sticky, worm-like, convex on top, flat on the bottom, swollen in the middle, with sparse bristles. The length of the last age larva is up to 16 mm. The head, thoracic, and anal bristles are black. There are two rows of black spots on the sides of the abdomen.
The pupa in the early stages is reddish, later turning yellow-white, and resembles the adult insect in shape.
Length is up to 10 mm, width is up to 6 mm.
The mating period begins on the 3rd to 5th day after the beetles emerge from the soil. Females lay eggs on the underside of the leaf blade. A cluster contains 28–30, and rarely up to 70 eggs. Throughout the summer, a female produces on average from 900 to 1600, sometimes over 2000 eggs.
In the temperate zone, 1–2 generations of the beetle develop per year, while in southern regions — 2–3. During the development period of the pest, all stages of its development can be seen simultaneously: imago (adult individuals), egg clutches, and larvae of four ages. The main damage to potatoes is caused by young beetles and larvae of the 3rd and 4th ages of the first generation: they inflict up to 90% of the damage to the leaf surface. The beetle hibernates in the soil in the imago stage at a depth of 20–40 cm and emerges to the surface when the average daily air temperature reaches 15°C, usually slightly earlier or simultaneously with the appearance of potato sprouts. The optimal temperature for the pest's development from egg to adult is 24–26°C, with a relative humidity of 60–75%. At temperatures below 14°C, its development slows down, and at high temperatures (above 38°C), mass mortality of eggs and larvae begins.
It is subject to external quarantine measures.
Distribution: Northern Tien Shan, Western Tien Shan, the Prefargana regions of Kyrgyzstan, Alai Valley
Insects of Kyrgyzstan