What kinds of insects are there?

Answer 1

There are millions of species of insect in 29 orders. How are there so many? Insects have very fast reproductive cycles. Each insect produces thousands of eggs per female individual. The faster an animal's life cycle the faster genetic mutations can enter the environment and thus the faster they can be selected or eliminated. Divergences and difference-arisings among fast reproducing organisms occur faster than other organisms because of the rapid reproduction. This is the best answer I can give, genetically, evolutionarily and species-divergently.

Additions to this explanation may include that insects are successful terrestrial organisms with a protective chitinous exoskeleton. Does this protect them enough from predators and climates, keeping them alive long enough and numerously enough to evolve rapidly and diversely? Insects have diverse ways of protection, from webspinners protecting themselves in their own web-blankets to ants with stings, catepillars with ingested and self-used poisons, moths' warning flashes of colour and 'false eyes' and bombadier beetles which fire boiling liquid at enemies.

Also, insects are (usually) flying. With this capability there is a great scope for niche occupying in the 3D world flight offers. Single trees at different levels can be captured as niches by different species. Also being so small may increase the scope of niche occupance. Different sorts of fields, rock-crevices, tree levels or any sort of undergrowth or even fresh water are all possible niches for insects, whose surface area is increased dramatically from the insects small-size point of view. With so much area to occupy, niche-divergences could occur at a very fast pace, evolving insects into their hugely multitudinous forms.

Another idea is arms race. Insects may be involved in arms races with plants. Plants continuously adapt to insects devouring them by producing greater and greater varieties and powers of toxins. Insects in response evolve immunities to these toxins and continue to devour unremittingly.

Maybe an extremely powerful force could be plant-insect pollination symbiosis. As the plants evolve differing flower structures, insects (in another sort of arms race) evolve anatomical structures to still be able to acquire nectar from the flowers they seek. The more this goes on, the more plants evolve, the more insects evolve.

Among the phenomenal array of insect species, all, some or none of these specialization-encouraging phenomena could be occurring. Any one explanation for the diversity of insects could be a single one of the above options, a combination or something slightly different that we do not know yet.

Answer 2

Many kinds. These are more primitive and don't pupate from a larva that looks very different from the adult: silverfish, mayflies, dragonflies, damselflies, stone flies, grasshoppers, aphids, cicadas, true bugs, cockroaches, mantids, scorpionflies, fleas.

From here on they metamorphosize and the larva looks very different: flies, hoverflies, mosquitos, wasps, bees, ants, beetles, butterflies, moths, lacewings.

Answer 3

about 1,382,000,000