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The weevil is an insect of the order Coleoptera. The weevil family is one of the largest among the Coleoptera (about 40,000 species). Most weevils have long, clearly geniculate antennae that can fold into special depressions on the snout. Many members of the species do not have wings, while others are excellent fliers.
Origin of the species and description
Photo: Weevil
The weevil was first described by Thomas Say in 1831 as a weevil from specimens taken in Louisiana. The first economic report on this insect was that of Asa Fitch of New York, who received infested beans from Providence, Rhode Island, in 1860. In 1891, J. A. Lintner, New York, proved that the bean weevil multiplied continuously in stored beans, distinguishing it from the famous European pea weevil.
Fun fact: Weevils are actually beetles. There are more species in this family than in any other group of beetles. Scientists estimate there are more than 1,000 species of weevils in North America.
Video: Weevil
There are 3 main types of weevils:
- Rice weevils are small beetles only 1 mm long. The adult is grayish-brown to black in color and has four reddish-yellow spots on the back. The larvae are white and soft, without legs. Weevil pupae resemble adults with long snouts, but they are white. An adult can fly and live up to five months. The female of this weevil lays up to 400 eggs during her life;
- Corn weevils were previously considered only a large variety of rice weevil due to their external similarity. It is slightly larger, up to 3 mm in length, and like the rice weevil, it is reddish-brown to black in color and has four red-yellow spots on its back. But its color is slightly darker than that of rice. The development rate of the corn weevil is slightly slower than that of the rice weevil. Its larvae are white and soft, without legs. The pupae also resemble the adults with their long snouts, and they are also white. The corn weevil is also capable of flight;
- granary weevils are more cylindrical than others and are about 5 mm long. Their color ranges from reddish-brown to black. The body length is approximately 3 mm, and the muzzle extends down from the head. Its larvae are white and soft, without legs, and the white pupae are similar to the pupae of other weevils. This weevil is unable to fly, so it can be found near areas it has infested. Adults can live up to 8 weeks, during which time the female lays up to 200 eggs.
What kind of elephant is inactive, when alarmed, it curls up its legs and falls, pretending to be dead?
Ilyadru
Elephant beetles, or weevils. Small elephants are similar to their huge namesakes - African or Indian elephants - in that the elephants' heads are elongated like a proboscis or a long nose. But that's where the similarities end. Most elephants are small bugs, up to 10 millimeters long. The elephant beetle is inactive, and when alarmed, it tucks its antennae and legs and falls to the ground, pretending to be dead. The acorn elephant can be distinguished by its very long, thin, shiny proboscis. At the end of the proboscis there are small but very strong jaws, turning the proboscis into a very advanced drilling apparatus. Such an apparatus is necessary for the female beetle to drill a passage in the acorn fruit, where she lays eggs. Drilling an acorn takes the beetle from 6 to 8 hours.
I'm the Starr
This is something indecent already!!!
Shmelik
baby mammoth from the Ice Age. or rather MAMMOTH.
Alex
These are beetles, elephant beetles or weevils. This is a common thing for beetles, the slightest threat - and they fold their legs and antennae and fall down from the stem or leaf. Then go find it in the grass or forest floor! You can lay a tarpaulin or polyethylene under a tree or bush and shake it by the trunk. Bugs are falling, just collect them1
Appearance and features
Photo: What a weevil looks like
Different species of weevils occur in a wide range of colors and body shapes:
- size: the length of weevils varies from 3 to 10 mm; many of them are oval insects;
- color: usually dark (brown to black);
- Head: The adult weevil has an elongated head that forms a snout. The mouth is at the end of the snout. In some weevils, the snout is the same length as the body. Another family of beetles, the caryopsis, has a different appearance. They do not have the elongated snout found in other weevils.
The survival of an adult weevil depends in part on its exoskeleton, or cuticle. The cuticle is composed of a mixture of chitin and proteins, which are organized into three layers: epicuticle, exocuticle and endocuticle. The cuticle undergoes a hardening process known as sclerotization and melanization, which requires the presence of the compound dihydroxyphenylalanine (DOPA).
The weevil's midgut contains small pouches that increase the intestinal surface area, improving digestion and nutrient absorption. At the tip of each cecum is a bacteriome, a specialized organ made up of cells called bacteriocytes that protect the endosymbiotic bacteria from attacking the host's immune system. Bacteriocytes not only contain endosymbionts in their cytoplasm, but also provide nutrients necessary to support bacterial growth.
Where does the weevil live?
Photo: Weevil beetle
In warm seasons, outdoors, weevils eat the leaves of trees, shrubs and plants. However, in the fall of this year, these plant-eating weevils begin to look for a place to overwinter.
Some species, such as the Asian oak weevil, are attracted to light. They gather around the doors and windows of houses. Homeowners sometimes notice hundreds of weevils clustered around the outside of their home. When weevils find cracks or holes around windows, they move inside the house. They also enter through broken vent screens or vents. They may also crawl under doors that have been damaged by the weather.
Fun Fact: Many of the weevils that invade homes spend the winter insulated inside the walls. The attic and garage are also common winter hiding places for weevils. These beetles can go through the winter without being seen by the homeowner.
However, some weevils find their way into the living space of the home. They may pass through a crack in the wall or in the space next to the pipe. They can crawl out through a gap under the baseboard. They may even use the light fixture hole to crawl out of the attic.
In winter, the living space of the house is warmer than the attic or garage. This can confuse the weevils. When they find themselves in a warm home environment, weevils begin to act as if spring has arrived and try to find a way to get outside.
Weevils that come to shelter indoors can infest every room in the house. They are often grouped in rooms with windows. Bugs gather at windows, trying to get outside. Homeowners find these weevils crawling along walls, window sills and ceilings.
What does the weevil eat?
Photo: Weevil in nature
Like other pantry pests, weevils feed on grains and rice, as well as nuts, beans, grains, seeds, corn and other foods.
Most weevils feed exclusively on plants. The fleshy, legless larvae of most species feed only on a specific part of the plant - that is, the flower head, seeds, fleshy fruits, stems or roots. Many larvae feed either on specific plant species or closely related ones. Adult weevils tend to be less specialized in their feeding habits.
Weevils live and feed inside the grains they eat. The female gnaws a hole in a seed or grain and lays an egg in it, then closes the hole, leaving the egg inside the grain or seed. When the egg hatches, the larva will feed on what's inside until it is fully grown. When the adult weevil grows, it eats all the grain.
Fun Fact: Because female weevils emit pheromones, male weevils will expect them to emerge from the grain and will immediately seek to mate with them to reproduce.
Homeowners may not see weevils when they gather around the house. But if the weevils manage to find a hole and enter the house, the owner will often find hundreds of insects crawling along the window sills and walls.
Features of character and lifestyle
Photo: Weevil insect
Outdoors, weevils can destroy garden plants. Indoors, these bugs are more of a nuisance than dangerous. Weevils contaminate food with feces and skins, causing more damage than they can eat. At home, weevils can be seen on packaged foods, and they can also come from outside. Once inside, the population can grow and multiply from foods that are nearby if they are not checked.
Some weevils can become structural pests. These are the weevils that frustrate homeowners because they often invade homes in large numbers. Some of them invade in the fall. They hide in winter and leave in spring. Others invade in the summer when the weather begins to warm up.
Adult weevils are nocturnal and seek shelter under plant debris during the day. This behavior is used for monitoring and control purposes. Weevils can be monitored using traps and insecticides applied when adult weevils are first caught. However, the most widely used method of trapping is through "covers" containing insecticide-laced potato foliage. Cover traps are especially effective just before potato plants emerge in new fields.
Prevention of infection
After successfully combating a weevil infestation or to prevent infection of your area, the following measures can be applied:
- Maintaining distance when planting crops that can be damaged by the weevil;
- Regular loosening of the soil and mandatory digging in late autumn;
- Cleaning the area from carrion and fallen leaves;
- Study and application of crop rotation rules.
When an area is infested with pests, an integrated approach is required to get rid of insects. The damage this beetle can cause cannot be underestimated, so at the slightest sign of its appearance, it is necessary to immediately begin combating weevils using any of the methods described above.
Social structure and reproduction
Photo: Weevil beetle
Weevil life cycles vary greatly by species. Some adults lay eggs on the ground near host plants in the spring. When the eggs hatch, the larvae burrow into the ground and feed on roots. Because the larvae are underground, people rarely see them.
Adults chew the outside of the grain and also lay eggs. Females can lay 300 to 400 eggs, usually one per cavity. The larvae develop through several stages (instars) inside the grains and also pupate in the kernel. They can complete a generation after a month in warm conditions. Adults often live 7 to 8 months, but some are capable of living for more than 2 years.
The egg, larval and pupal stages of weevils are rarely found in grains. Feeding takes place inside the grain and the adults cut holes for exit. The exit holes of the grain weevil are larger than those of the rice weevil and tend to be more ragged rather than smooth and round.
The females drill a tiny hole in the grain, place the egg in the cavity, then seal the hole with a gelatinous secretion. The egg hatches into a young larva, which spreads to the center of the nucleus, feeds, grows and pupates there. New adults have openings to emerge from the inside, then go off to mate and begin a new generation.
Female granary weevils lay between 36 and 254 eggs. At a temperature of 23 to 26 degrees Celsius, relative humidity of 75 to 90%, eggs are hatched in wheat with a moisture content of 13.5 to 19.6% for 3 days. Larvae mature in 18 days, and pupae in 6 days. The life cycle is 30 to 40 days in summer and 123 to 148 days in winter, depending on temperature. It takes about 32 days to complete the life cycle. Both barn weevils and rice weevils feign death by bringing their legs close to their body and pretending to fall.
Many larvae spend the winter in the ground and become adults the following spring. However, adults that emerge in the summer or fall may enter homes for shelter. Some, like the Asian oak weevil, are attracted to light and are drawn into homes at night. Others may be attracted by the warmth from the home.
Folk methods of struggle
Chemical treatments, which not every gardener likes, can be replaced with fairly effective folk methods, one of which is the mechanical destruction of elephants. To do this, in the evening, under each bush of the plant, you should spread bedding, on which you need to shake off the bugs that have not yet woken up in the early morning. Then all this wealth should be carefully burned. At the same time, every evening you need to collect fallen fruits and get rid of them, especially rotten ones.
It is recommended to spray plants with mustard solution. To prepare it, 100 grams of powder should be diluted in 3 liters of water. As an analogue, you can also use herbal infusions of tansy, hot pepper and wormwood - effective means of repelling bugs.
Ash in its pure form is effective, scattered around the bushes in a thick layer in early spring. Also, some gardeners recommend trying to treat the plants with an adhesive solution of laundry soap combined with three kilograms of ash. The disadvantage of folk remedies is the short effect - until the first rain, which washes away all previous efforts. Therefore, such folk procedures should be performed regularly.
Natural enemies of weevils
Photo: What a weevil looks like
Weevils have many natural enemies.
Insect predators include:
- spiders;
- ground beetles;
- predatory nematodes.
Animal predators include:
- chickens;
- bluebirds;
- warblers;
- wrens and other birds.
Red fire ants are effective predators of the cotton boll weevil in eastern Texas. In 11 years, weevils suffered no economic losses due to mortality caused primarily by ants. Removing the ants resulted in increased crop damage from the weevil. Insecticides used for cotton pests significantly reduce ant populations. To benefit from this effective ant predation, unnecessary insecticide applications must be eliminated.
The main enemies of weevils are people who try to get rid of them. The simplest and most effective measure is to find the source of infection and quickly get rid of it. Use a flashlight or other light source to thoroughly inspect all food storage areas and food items. If possible, dispose of heavily contaminated food in wrapped, heavy plastic bags or sealed trash containers, or bury it deep in the soil. If you detect an infestation early, disposal may be the only solution to correct the problem.
Use of chemicals
The most radical and most effective method of combating weevils. Spraying with insecticides is carried out several times a year, at certain intervals:
Primary – a week after the expected start of plant flowering;
Secondary - a week or two after the start of flowering;
Tertiary – in the middle of the season when the green mass of plants is damaged.
It is worth considering that insects gradually develop tolerance to the insecticides used, so the drug chosen for treatment against weevils must be changed periodically.
