Summary
Six-legged arthropods with three body parts, often with wings, the most diverse animal group.
In depth
Three body regions (head, thorax, abdomen), three pairs of legs, usually two pairs of wings, tracheae for breathing and Malpighian tubules for excretion. Over a million named species. Important as pollinators, pests and disease vectors.
Insects have compound eyes, antennae and a tracheal system. Wings evolved once. Their success is due to small size, flight and adaptability.
Key idea: insects pollinate most flowering plants.
Insects are the most diverse group, with over a million described species. Wings, which evolved about 400 million years ago, allowed escape and dispersal. Mouthparts are modified for chewing, sucking, siphoning or lapping. Tracheae deliver oxygen directly to cells through spiracles, which limits body size (though higher oxygen in the Carboniferous allowed giant dragonflies with 70 cm wingspans). Insects have compound eyes, antennae with chemoreceptors and complex behaviours.
Orders include Coleoptera (beetles, the largest), Lepidoptera, Diptera, Hymenoptera and Hemiptera. Insects pollinate about 75 percent of crops, but also eat crops and spread disease. Declines in insect biomass reported in some regions raise alarm. Entomophagy is a possible sustainable protein source.
Example: honeybees communicate the location of food through the waggle dance, deciphered by Karl von Frisch (Nobel Prize 1973).
Frequently asked questions
What is Insects?
Six-legged arthropods with three body parts, often with wings, the most diverse animal group.
Which area of biology covers Insects, and how advanced is it?
Insects is one of the 53 topics in Zoology & Animal Diversity. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Arthropods, Animal Kingdom, Vertebrates and Invertebrates.
Can you give an example of Insects?
Mosquitoes transmit malaria and dengue.
What should I learn before Insects?
Insects is a Beginner topic, so no earlier topic is required. Other Beginner topics in Zoology & Animal Diversity that pair well with it include Animal Kingdom, Vertebrates and Invertebrates, Sponges.
What topics are related to Insects?
The closest topics to Insects are Arthropods, Animal Kingdom, Vertebrates and Invertebrates, Amphibians. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Insects?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Insects. To practise the whole of Zoology & Animal Diversity, use the Zoology & Animal Diversity quiz.
How is Insects different from Arthropods?
Insects: Six-legged arthropods with three body parts, often with wings, the most diverse animal group. Arthropods: Animals with jointed legs, exoskeleton and segmented bodies, the largest animal phylum. Read both side by side and note what each one explains.
How should I study Insects step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Arthropods and explain the difference aloud. Finally, take the Zoology & Animal Diversity quiz and come back to this page for any question you miss.