How do insects reproduce and develop?

         Scientists have studied more than 800,000 species of insects. Do you know how they reproduce and develop?

          Reproduction in insects is usually sexual, the male inserting sperm into the female’s body. The fertilized eggs are usually not tended by the insects, but they develop near or in a source of nourishment and protection. In some cases, fertilization is external. This means that the female lays the eggs and then the male fertilizes them. Some insects produce eggs which develop into adults without being fertilized. This is a type of asexual reproduction and is known as parthenogenesis.

          As an egg develops, it goes through several stages before becoming an adult. Some primitive insects develop directly from the eggs. Most of them, however, go through several stages of development called metamorphosis. In complete metamorphosis, there are four stages of development: egg, larva, pupa and adult. In incomplete metamorphosis there are three stages: egg, nymph, adult. The nymph is like a small adult. As the insect goes through its development, it moults several times. The entire process of metamorphosis may take a few days or several years depending on species and environmental conditions. Many insects lay eggs which can survive the winter or other unfavourable conditions.

        

          Insects are both harmful and useful for us. Some of the harmful insects damage the crops and plants. Some others are germ-carriers. They spread diseases by causing infection through micro-organisms such as bacteria, fungi, viruses and worm like parasites.

          As far as their usefulness goes, they are responsible for most of the pollination of plants. They serve as food for birds. In some countries insects are also used as food by human beings. Insects also provide us with some useful materials such as silk, honey and wax. They are also used in dyes, shellacs, medicines and many other products. You will be surprised to know that the eyes of some insects are made up of upto 30,000 tiny lenses called facets.