When you see the long tube extending forward from a weevil's head, you might think of an elephant's trunk. However, you must not mistake the long tube on the weevil's head for its nose! This long tube is its mouthparts and is also the main identifying feature of the weevil. Another feature of it is that the antennae are on the snout, which is rare among other insects. In addition, its tubular head can rotate left and right, which is very flexible, just like the large cranes often seen on construction sites, which is very interesting. The weevil, also known as the weevil, has a special body shape as an adult and is famous for its long mouth. Its mouthparts extend into a protruding trunk-like shape, which is called the head tube. The head tube of some species is almost as long as the body, which is very strange. Because its head tube is shaped like an elephant's trunk, people call it a weevil. Weevils are the largest family among Coleoptera insects and the most diverse group in the insect kingdom. There are more than 60,000 known species in the world, and about 2,000 species have been recorded in my country. Their individual differences are very large, and small ones Only 1 mm, the largest one can reach 6 cm.
Weevils mainly harm flowers, trees and fruit trees. The larvae are fat and bent into a "C" shape, with a particularly developed head. They can penetrate into the roots, stems, leaves or grains and beans of plants and feed on them. They are major pests on economic crops.
Weevils do not bite and have no odor, so large weevils are often caught, raised and played with by people.
1. Life habits of weevils
Weevils are dull and move slowly. But some big-eyed elephants are agile and their flying power can be compared with that of tiger beetles. Many weevils have degenerated hind wings and cannot fly, so they live on the ground. Species with hind wings are generally not good at flying and cannot easily escape enemy attacks because their hind wings are difficult to unfold. In order to escape attack, when they sense a danger signal, they suddenly drop from their host into the grass and pretend to be dead to protect themselves. Suspended animation is more common in weevils than in other beetles. The pseudoanthropy of Cryptobeak Elephant and Turtle Elephant is even more obvious. Their chests have long or short pectoral grooves. When in suspended animation, their beaks and antennae are incorporated into the thoracic groove, and their feet are tightly folded, causing their enemies to mistake them for a particle of bird droppings or a clod of soil, thus escaping sight and avoiding danger.
The vast majority of weevils are terrestrial, have no obvious phototaxis, and have no obvious tendency to flowers. Only rice weevils and water weevils are aquatic and have obvious phototaxis.
Weevils reproduce sexually, but species of the genus Aurorhinus reproduce parthenogenetically. The chromosomes of these species are polyploid, with 33, 44 or 55 chromosomes, while their closely related sexual species are all diploid (22 chromosomes).
Most weevils have one generation per year. Mongolian earth elephants, gray elephants, pine bark elephants and oak elephants have one generation every two years. They overwinter as larvae in the first year and as adults in the second year. There are two generations of small egg elephants in one year. The first generation is parasitic on mulberry trees. , the second generation is parasitic on cotton. There are four generations of green duckweeds a year, all of which are parasitic on green duckweeds. Corn weevils and rice weevils occur several generations a year and occur continuously in grains. Most weevils overwinter as larvae, while the weevils Overwinter as larvae, weevils and elmweevils overwinter as adults. We know only the weevils that overwinter as eggs or young larvae.
There are two ways for weevils to lay eggs: one is to lay eggs directly in the soil or outside the host plant, and the larvae live outside the host; the other is to dig them out with their beak before laying eggs. A hole is formed and eggs are laid inside the host plant, where the larvae live.
2. The economic significance of weevils
The feeding habits of weevils are complex, and all plant roots, stems, leaves, flowers, fruits, seeds, seedlings, young shoots, young shoots, etc. are not immune to their harm. Most of the weevils eat inside the plants, which not only causes serious damage, but is also difficult to control, so it is of great significance to agricultural and forestry production.
Nearly 20 species of destructive pests such as weevils that damage seeds, seedlings and tree trunks have been recorded in the literature, such as rice weevils and corn weevils that damage seeds, two types of beet weevils that damage seedlings, and poplar trunk weevils that damage poplar trunks. These five weevils represent three different categories of pests, all of which are of great economic significance. However, the economic significance of rice and corn weevils is particularly important. Because their damage is destructive, the part they damage is food and seeds, and the economic status of their hosts plays an important role in people's lives and food production. Although the two sugar beet weevils and the poplar weevil are also destructive pests, their harmful parts and the economic status of their hosts have little impact on people's lives and the development of agriculture and forestry. This shows that the economic significance of weevils can only be fully explained by considering three aspects: the degree of damage, the parts damaged and the economic status of the host.
Among the important pests, it is well known that the types that damage seeds and fruits are more than those that damage other parts; the types that damage woody plants such as forests and fruit trees exceed the types that damage crops. These facts are well known. Most weevils are harmful; only a few species are beneficial. Since the Ming Dynasty, the working people of our country have used gall-bearing motherwort as medicine. According to specimens provided by the health department in Changsha, Hunan and the Nanchong Drug Planting Experimental Site in Sichuan, the weevil in the gall was identified as the weevil. This insect lays its eggs in the ovary of mosquito weed or water bittern. As the larvae develop, the ovary develops into worm tumors. Before the adults emerge, people harvest the whole plant and dry it in the sun to stop bleeding, activate blood circulation, reduce swelling and relieve pain.
Canada has successfully used conical broad-billed elephants to control a harmful weed called thistle in pastoral areas, saving livestock production. In my country, the chrysanthemum weevils that parasitize the flower heads of Asteraceae plants such as Echinacea and Asteraceae have a very similar relationship to the above-mentioned weevils and their hosts. In vast agricultural and pastoral areas, if thorn weeds and reeds breed and cause disasters, chrysanthemum elephants are valuable in destroying these harmful weeds.
animal tags： Weevil nose mouthparts
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