Since people have learned how to grow grain, they have had problems with the pests of their stocks. Thus, even the ancient Egyptians and Romans with displeasure found beetles in their granaries, which spoiled their food. These unpleasant cosmopolitan insects still pose a threat to barns around the world.
Let us consider in more detail what is a barn, a grain weevil. Like all beetles, the weevil belongs to the order of beetles. It got its name because of the characteristic shape of the head. And this is no accident: at the end of the so-called roach is a mouthpiece of a gnawing type, with the help of which the pest is introduced into the soft parts of the grain.
The beetle is voracious and omnivorous, it affects any grain and leguminous crops: rice, buckwheat, wheat, beans, peas, etc. The larva inflicts the greatest damage to products. This pale worm-like creation reaches a length of 3-4 mm. On the anterior segment of the body, it has short legs and a head, equipped with mandibles.
Having barely hatched from the egg, the larva immediately bites into the grain and eats it almost to the shell.
Depending on the temperature, the larva is engaged in its destructive activity from twenty days to three months, after which it pupates in a chamber, which it does in advance and clogs with its excrement.
In the pupal state, the insect can also spend different times - from one week to three.
The pupa resembles an adult beetle: it has six legs, thin wings and reduced elytra, by the way, growing, the beetle can not fly. Having matured, the insect gnaws at itself an exit and leaves grain in which developed.
Mature beetles (imago) are also harmful to grain stocks. Their life expectancy is quite significant - up to one and a half years. Given that the female weevil can lay up to 250 eggs, one can imagine what damage this beetle inflicts. An adult individual has an oblong body with a length of 3.5 to 4.5 mm. The chitinous cover of young individuals is light brown, with age it darkens.
Sexual dimorphism is weakly expressed: in the female, the abdomen is straight, and in the male, the abdominal segment is bent down. Gnawing a hole in the grain, the female lays one egg at the bottom, and so many times in a row. Egg chamber is covered on top with a thin film. This is hardened mucus. After a week or two, the larva hatches from the egg, and the life cycle of the pest is repeated.
The size of the rape sawfire reaches only 6-8 mm, but it can destroy the entire cruciferous crop. Read more about this insect here.
Shchiten is a crustacean animal that can harm rice crops. How to deal with Shchitney, read the article on http://stopvreditel.ru/rastenij/selxoz/shitni.html link.
Advantages and disadvantages
Weevil - being extremely adapted to changing environmental conditions. He feels comfortable in the temperature range from 16 to 28 degrees, but can tolerate more extreme temperatures. It is also not demanding of environmental humidity, since it spends most of its life inside the grain under the protection of its dense shell, exine. However, too dry air is detrimental to most insects, including the weevil.
The duration of the life cycle of a beetle depends on external conditions: the milder they are, the faster the insect reaches puberty. If the temperature regime does not suit him, then the pest can fall into anabiosis, then to return to full-fledged life. Thus, the pest is able to give 2-3 generations per year. Both beetles and larvae winter inside the grains. Also, adult insects feel good in crevices, cracks and other secluded places.
Together with the damaged grain, as well as with the inventory, weevils migrate from one storehouse to another, affecting agricultural products.
Since the man is forced to tolerate the presence of weevil in his barns, he has developed a strategy to combat this pest. For prevention, the following means of struggle are used:
- cooling or, conversely, heating the grain and its products before storage,
- its drying because insects are critical to environmental humidity
- cleaning grain from debris and impurities,
- cleaning storage and processing by disinsection. For this purpose, preparations based on phosphorous hydrogen (phosphine) are used, which are sprayed or used in the form of an aqueous solution,
- the use of ionizing radiation is at the stage of development and, possibly, will be applied in the future.
Weevil is started up not only in barns, but also in our home. In order for the beetle not to spoil our stocks, there are proven and harmless methods:
- put the cereal in the freezer for a while and then pour it into hermetic containers,
- since the insect does not tolerate strong odors, you can put peeled garlic cloves, bay leaf or sprigs of lavender into the grits,
- Cabinets where you store supplies should be washed with soap, soda, or vinegar solution and well ventilated.