All about insects
In terms of numbers of species, insects form the largest class in the Arthropod phylum – both globally and in Finland. More than 900,000 insect species have been identified, but estimates of the actual number range between 2 million and 30 million species. Other types of arthropod are the entognathans, arachnids, crustaceans, and myriapods. The most important characteristics of insects are a body that consists of a head, thorax and abdomen. They have three pairs of legs located on the thorax. Insect larvae can also have several pairs of false legs on their abdomen. As adults, many insects have two sets of wings.
We see insects in all types of habitats and they use almost anything as food: living and dead plants, animals and mushrooms as well as manure, blood and other bodily secretions.
Metamorphosis in insects can occur in three forms: little or none (for example, silverfish, firebrats), gradual (true bugs) or complete (butterflies and beetles). The majority of insects belong to orders that undergo complete metamosphosis. As is the case with all arthropods, insects have to moult – or shed their skin – as they grow. The number of times an insect moults during the larva stage varies greatly between different species.
The importance of insects to biodiversity cannot be overemphasised. They hunt other insects and are prey for many organisms, they pollinate plants, improve the soil, and recycle nutrients. These services are also extremely important for people. Without them, the conditions for humans to live on this planet would be much poorer.