Carpenter beetle - ruthless predator and its offspring

Swimmers are a common family of beetles that have adapted to life in water. They are characterized by a streamlined body shape that simplifies movement in a pond. Predatory beetles attack insect larvae and larger prey - fry and tadpoles. Universal insects not only swim, but also fly well. Bug beetle bordered by one of the largest representatives of the family. imago length 30-37 mm. A distinctive feature of the species is a wide yellow-orange edging running along the body.

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Banded swimmer (Dutiscus marginalis) belongs to the family swimmers. The Latin name for the genus Dutiscus comes from the Greek word duticos, diving. Oval weakly convex body 27-35 mm long. A wide, flat head to the eyes is pulled into the prothorax. On the sides are large convex eyes. Antennae thin, filiform, composed of 11 segments. The oral apparatus consists of the upper and lower lips, strong mandibles and maxillas.

Pronotum and elytra bordered by a wide yellow-orange stripe. The main color is black or brown with a green tint. The lower body is yellowish. Elytra tightly inserted. In males they are smooth, and in females they are covered with longitudinal grooves. insects have leathery wings, folded and hidden under the elytra in a calm state. The front pair of legs is used for clinging to plants, crawling on land and holding prey. On the forelimbs of males there are suction cups to hold the females during mating.

Information. Suction discs secrete a special secret that allows males to stay on the body of females for several days.

The hind legs are adapted for swimming, they are long and flat. The rowing surface of the limbs increases the crest of long hairs. During swimming, the limbs move simultaneously. The middle pair of legs is used as a rudder to turn up or down. The abdomen consists of 8 segments; each has a pair of spiracles. The lower part is protected by chitinous cover, and the upper elytra.

Habitat

Banded beetle found throughout Europe and Asia. Insects live in Siberia, brought to North America. In the Far East lives a subspecies of swimmers, which differs in large sizes - 33-37 mm.

Lifestyle

Beetles settle in fresh stagnant water or bodies of water with a weak current and a large amount of vegetation. You rarely meet a fringed swimmer in shallow water. Adults prefer to leave the pond at night. They make long flights in search of new favorable habitats. before takeoff, empty the intestines and fill with air. When landing, they simply fall head down. The life expectancy of a male is 1 year, females 1.5-2 years.

Interesting fact. Swimmers often fall on the highway and glass roofs, confusing their luster with the surface of the water.

Predatory imagoes attack any prey of the appropriate size: insects, snails, newts, tadpoles of fish fry. Cannibalism often occurs, adult beetles eat their own larvae. They consume not only live prey, but dead animals floating in the water.The green color of the body makes the hunter invisible among plants. He quickly rushes to the passing victims. Insects and tadpoles are torn apart by strong jaws and eaten completely. After feeding, the swimmers clean the mouth with the front paws.

Beetles are extremely voracious, they rush to affordable prey, even full. Indiscrimination sometimes leads to death, for example, the larvae of ladybirds are poisonous to them. The swimmer bordered is capable of starving for 1-2 months.

Breathing process

Adults breathe atmospheric air. To replenish its reserves stored under the elytra, the beetle exposes the posterior end of the abdomen above the surface of the water. Through the spiracles, air enters the tracheal system. If it is not possible to float, swimmers use oxygen dissolved in water. They expose an air bubble from under the elytra. Gas exchange occurs through its walls, then the bubble is drawn back. This is an incomplete breath, it does not replace the atmospheric air.

Information. The bug takes enough air for 8-10 minutes under water.

Breeding

The mating period begins in the spring, after leaving hibernation. The male climbs onto the female and is held on its elytra with the help of flat discs with suction cups on the front legs. During the copulation, he has the ability to expose the abdomen from the water and breathe. Saka is deprived of such an opportunity. If several males attack her, then after the second or third mating, she dies from suffocation. The only available way to get oxygen is to release a bubble for gas exchange in water. If fertilization occurs in the fall, the resulting sperm retain the ability to fertilize for six months.

In April-May, egg laying on the stems and leaves of aquatic plants begins. Masonry is done by young and overwintered females twice. Sharp ovipositor eggs are placed inside the plant tissue. In one day, up to 30 pieces are laid, for the entire period - 1000 eggs. The masonry is placed on any plants encountered by the female, reeds, marigolds, arrowheads. Lumps of algae can be used. The eggs are large, 6-7 mm in size, light yellow. The plant protects them from being eaten and mechanically damaged.

Larval development

The hatching larva is completely different from the imago. Coming out of the egg, it falls to the bottom, where it rests 30-40 minutes. Then it rises vigorously to the surface and takes the first breath using the spiracles at the end of the abdomen. It is born 10 mm long, by the end of development it increases 5 times. The larva has a flattened head, curved upper jaws, an elongated prothorax. Three pairs of swimming legs help you move around quickly. The abdomen consists of 8 segments. On the latter there are caudal appendages, anus and spiracles.

The swimmer's larva is no less dangerous predator than its parents. Strong curved jaws, it reliably holds the prey, giving no chance to escape. Through channels located in the stings, a poisonous liquid enters the victim’s body from the esophagus of the larva. It is rich in enzymes that turn protein into a liquid state. Little hunter sucks nutritious gruel, leaving only the skin. At low temperatures + 4 ° C, the larvae stop feeding. Starvation may last several weeks.

Information. Beetles and larvae destroy weak and sick fry in water bodies.

Doll

Approaching the final stage of development, the larva becomes restless, changes externally. She creeps out on land and looks for a hole for pupation. The larva builds a spherical cradle from the earth and its own secretions. Pupa phase lasts 2-4 weeks. Young beetles are painted white. Within a few hours, parts of their bodies turn yellow first, then acquire a dark shade with a yellow border around the edge.

Once out of the ground, the swimmer crawls to the water. An interesting insect is often found in aquariums. Beetles do not require special care, unpretentious in nutrition. They live in captivity for 3-4 years.