Why are there so many insects (the secret of thriving insects)

In our daily lives, we are directly or indirectly related to insects all the time. Especially in the season after spring and before the harsh winter comes, there are so many insects that you can see them everywhere. In addition to being bitten by mosquitoes and harassed by flies, if we are not careful, insects may fly into our eyes, we may be stung by bees, or bitten by poisonous insects. Even stored food and clothing are often eaten by pests. Other insects are pleasing to our eyes. For example, butterflies are compared to flying flowers; cicadas are known as the singers of nature; crickets are known as loyal and brave generals; there are also bees that make honey, silkworms that spin silk, Glowing fireflies, patrolling dragonflies in the sky, beautiful flower ladies, etc. We already know that there are currently about 1 million named species of insects, and more than 1,000 new species are discovered every year. It is still unknown how many species of insects there are in the world, but it is estimated to be between 3 and 10 million species. Not only are there many types of insects, but there are also many individuals of the same insect, and some individuals have an astonishingly large number.

So, why are there so many insects? This can be analyzed from several angles.

1. Insects are the only winged animals among invertebrates. Flight enables insects to be more skilled than land animals in foraging, courting, avoiding enemies, and expanding their distribution range.

2. Insects generally have relatively small bodies.

(1) Small bodies only need a small amount of food to complete growth and development. For example, one cabbage leaf can support thousands of aphids, and one grain of rice can support several rice elephants.

(2) Small body makes it easy to hide. Hundreds of aphids, whiteflies, scale insects and other tiny insects can be hidden on the back of a leaf; a family of tens of thousands of ants can be accommodated under a brick; under a tree In the cave, dozens of insects and hundreds of individuals can live together at the same time. Its small body also allows it to hide in food, thus gaining the benefits of moisturizing and avoiding enemies.

(3) Small size is very beneficial to the migration and spread of insects. Winged insects can use air currents and wind to migrate to great distances. Even wingless species can be carried to other places due to their small size through the exchanges of birds, beasts and humans. This greatly expands their living range and increases the number of choices suitable for their living environment. Opportunity.

3. Wide food source. The differentiation of insect mouthpart types, especially the switch from eating solid food to eating liquid food, has greatly expanded the range of food and improved the relationship with the host - under normal circumstances, the host will not die due to losing part of its juice, but will instead Come over and affect the survival of insects. Insects have a wide range of food sources and can be said to be everywhere. From indoors to outdoors, from poultry houses to livestock sheds, from plains to mountains, from vegetable fields to orchards, from farmland to forests. From plant roots to stems, from branches and leaves to flowers and fruits, from living animals to dead bodies and various humus, there is nothing that is not food for insects. However, different types of insects have their own choices. It can be said: "Everyone likes radish and cabbage." "Insects not only have a wide range of food sources, but some species also have diverse feeding habits, especially herbivorous insects. There is a kind of gypsy moth that can eat the leaves of 485 kinds of plants, and the Japanese chafer can eat 250 kinds of plants. On the other hand, there are more than 200 kinds of pests in corn, more than 400 kinds in apples, 170 kinds of pests in pine trees, more than 650 kinds of pests in elm trees, more than 450 kinds of pests in willow trees, and more than 1,400 kinds of pests in oak trees.

4. Insects have amazing reproductive capabilities.

(1) Insects have extremely strong reproductive capabilities. Generally, insects can lay hundreds of eggs in their lifetime. For example, cutworms lay an average of more than 800 eggs. The queen of bees can lay 2,000 to 3,000 eggs every day. A termite queen can lay millions of eggs in her lifetime, averaging 60 eggs per second. In the five months from April to August, a pair of flies can produce 1.9 trillion offspring if they do not die. In the 150 days from mid-June to mid-November, a parthenogenetic cotton aphid in Beijing had six trillion offspring, assuming all of its offspring were alive. It can be seen that the reproductive capacity of insects is unmatched by any other animals.

(2) Reproductive methods are diverse. The reproductive modes of insects include hermaphroditic reproduction, parthenogenesis, polyembryonic reproduction, viviparous reproduction and larval reproduction (for details, please see "Various Reproductive Modes").

(3) Insects are small and develop quickly, that is, they can complete many generations in a unit of time. For example, some insects in the south can have about 10 generations a year. These conditions are linked and become important conditions for insects to have extremely high reproductive rates. Therefore, in a natural situation with a changeable environment and numerous natural enemies, even if the natural mortality rate reaches more than 90%, it can still maintain a certain population level.

5. Changeable self-defense ability and strong adaptability. Insects have been on the earth for at least 350 million years. In the long-term evolution of adapting to the environment, they have a variety of self-defense abilities to protect themselves from natural enemies (see "Weird Ways of Self-Defense" for details). Insects also have strong adaptability. Some species can tolerate severe cold temperatures of -50°C, while others can inhabit deserts or hot springs with temperatures as high as 49°C. Some flies can live in pure salt and pure oil; grain weevils can live in pure carbon dioxide; other insects can move freely even in long-term water shortages.

6. Complete metamorphosis and developmental stages. The vast majority of insects belong to the complete metamorphosis category, that is, the larvae and adults are clearly differentiated in terms of shape, feeding habits, and behavior. This differentiation is achieved through a stationary pupa stage. In this way, it not only expands the food sources of insects of the same species, meets the nutritional needs of insects, but is also highly adaptable to the external environment.

Relying on their superior adaptability and tenacious survival skills, insects have continuously developed and grown over the long history and become the most prosperous family "occupying" the earth. A writer once wrote: "Insects appeared earlier than humans. Their tenacity may allow insects to live further than humans. There are many mysteries here that need to be revealed by humans." "

animal tags： insect reproduction survival invertebrate development