The first category includes insects that harm various crops and forest trees, or insects like mosquitoes, fleas, flies and cockroaches that suck human blood, spread pathogenic bacteria or disturb our peace.
The second category can be divided into beneficial insects and useful insects. The former is a predatory or parasitic insect that preys on pests or parasitic pests and is a so-called beneficial insect in a narrow sense; The latter are insects that directly benefit us, such as bees and silkworms (silkworm babies).
The third category is insects that seem to have no direct relationship with us, neither good nor bad. Insects have a strong reproductive ability. A female can lay dozens or even thousands of eggs, and reproduce several times a year, and the number of offspring is very considerable. Take radish aphid, a common vegetable pest in vegetable garden as an example. It completes a generation in two weeks and gives birth to about 50 offspring (it is oviparous and directly gives birth to young nymphs). It is estimated that the total weight of offspring born one year later can reach 2.5 million tons. If you arrange them one by one, you can circle the earth 6.5438+0 million times. However, we don't see radish aphids everywhere in the whole garden, because natural enemies such as ladybugs and aphid-eating flies are waiting for opportunities to prey on them, and many kinds of insects are parasitic on them, which makes them unable to reproduce freely. The same is true for the reproduction of other pests, because they are besieged by natural enemies and parasites, so the usual incidence keeps a certain balance. From here we can see how important beneficial insects are to human beings.
Insects are good for us in many ways. In addition to the above, many things we come into contact with in our daily life are related to insects. For example, honey, beeswax, royal jelly and propolis come from bees, and silk is made from silk vomited by silkworm babies. Chocolate and chewing gum are instant substances in the mouth and shellac secreted by wax insects and rubber insects.
Insects can also be eaten. Indigenous people all over the world eat more than 500 kinds of insects. Because insects develop rapidly, reproduce strongly and contain nutrients, experts are actively developing the edible value of insects to prepare for the possible food crisis in the future.
Insects have a long history as medicinal materials. There are 265,438+0 species of insects listed in Shennong's Herbal Classic, 73 species listed in Li Shizhen's Compendium of Materia Medica in the Ming Dynasty, and 65,438+065,438+0 species were added in the later Supplement to Materia Medica.
With the progress of chemical analysis and efficacy testing technology, it is believed that it is not difficult to find species with good efficacy and development and utilization value in the existing pest list. At present, the most famous and expensive medicinal insect is Cordyceps sinensis.
Many insects play an important role in the natural ecosystem. If saprophytic, carrion-eating and dung-eating insects do not act as scavengers in the wild to deal with fallen leaves, animal carcasses and dung, the wild will be full of these corrupt substances.
In addition, although the pollination behavior of insects is often ignored by us, many experts believe that the greatest contribution of bees to human beings is actually pollination, rather than providing honey and other products. Insects also have ornamental value. They can be used as pets, teaching materials for nature observation and even experimental animals. It is of great use to think about insects carefully. The use of insects to human beings seems endless.