Insects come in a variety of sizes.
Since an insects skeleton is on the outside of its body, the mechanics of support and growth are such that the animal is limited to a relatively small size. This small size enables insects to live in places that would not be available to other animals. The key is chitin a light but structurally superior substance that composes the majority of the body wall and exoskeleton. This, combined with the internal muscle attachments that give insects proportionally better leverage and strength, enable insects to move or lift weights many times their own weight. Therefore, carrying their own body weight is a minor problem.