There are lots of insects on Earth, andthe number is unknown. What we do know is that there’s about 1.4 to 1.8 million different species of insects. Within each species there are certain orders. Confused? It’s alright.
Think of flies. There are actually hundreds of different kinds of flies, and flies are just one kind of insect. So you can see that there are billions and billions of insects out there.
But what insects are there the most of? This is much easier to answer and it might surprise you. Here are the 3 most common insects on Earth:
#1 – Beetles
The largest group of insects on Earth is called Coleoptera, or beetles. In fact, beetles make up the largest group of insects around, coming in at a whopping 25% of any order. There are 4 distinct suborders of beetles, and they number close to 4 million. You can find beetles everywhere but in the oceans and in the most frigid of places. Most break down matter and really constitute a large kind of ‘disposal unit’ for the planet.
Beetles are a huge part of the food chain, making up a large portion of the diet for many types of vertebrates and invertebrates. All beetles have an exoskeleton, and many species have armor-like shells that look quite formidable. Still, all follow the basic insect form of a head, thorax, and abdomen.
#2 – Flies
The second largest group of insects on the planet is called Diptera, or flies. These pesky insects are everywhere, and they aren’t just the common house flies that many think of. Diptera encompasses dragonflies, mosquitoes, butterflies, fireflies, gnats and more. It’s estimated that there are 240,000 different flies in the order and less than half of them have been fully described by scientists.
Flies do just what their name implies – they fly. Wings sprout from their thorax while the head holds antennae. These two tagmas, or segments of the fly, are what is responsible for flight. All of the muscles and physical flight control mechanisms are in the thorax while all the neurons responsible for controlling things like pitch, roll, and self-motion are in the brain. It is known that the H1 neuron in the flies’ brain is responsible for this flight stabilization.
What is so interesting about flies, and what many people don’t know, is that flies only eat liquids. Yes, they can’t eat because they don’t have teeth. They may consume small granular objects but these are broken down into liquid form.
#3 – Bees & Ants
No, it’s not a tie for third place. The third largest order of insects is called Hymenoptera, which comprises bees, ants, wasps, and sawflies. There are known to be 150,000 different forms of these insects. They are very similar to flies in that many can also fly around and they have the same basic body structure as well.
Most insects in hymenoptera will eat plant matter. What is interesting is what their kids do. Many species will lay eggs in a carcass of some sort. The eggs will hatch and the hatchlings will eat their way out, growing larger and stronger in the process.
Beetles have about 25,000 different species, flies have about 20,000 and ants & bees come in around 18,000. So overall these 3 larges groups of insects make up around 53,000 different species in the insect family.
Erwin, T. L. 1983. Tropical forest canopies: the last biotic frontier. Bulletin of the Entomological Society of America, Volume 29: 14-19.
Hoell, H.V., Doyen, J.T. & Purcell, A.H. (1998). Introduction to Insect Biology and Diversity, 2nd ed. Oxford University Press. p. 493-9.
Janzen, D. 1976. Why are there so many species of insects? Proceedings of XV International Congress of Entomology, 1976: 8494.
Oldroyd, Harold. The Natural History of Flies. New York: W. W. Norton. 1965. p. 79-81.
Powell, Jerry A. (2009). “Coleoptera”. In Vincent H. Resh & Ring T. Cardé. Encyclopedia of Insects (2nd ed.). Academic Press. p. 1132.