A short anatomy lesson this morning.
All insects have six legs, three main body segments (head, thorax, abdomen) and a pair of antennae. All wings and legs are attached to the thorax. Spiders are commonly confused with insects, as both are arthropods, but spiders have eight legs and two main body parts: cephalothorax and abdomen. Insects belong to class Insecta, and spiders belong to Arachnida.
Most insects have wings of some sort, but these vary in number. Some insects with wings are flightless, others have wings that function as protective coverings, such as beetles. The beetle order "Coleoptera" means "sheath wing", and refers to the outer set of hard wings that protect the body and cover the second set of wings used for flight. Other types of wings include the "scaled wings" of butterflies and moths, which are covered in tiny overlapping scales that create beautiful wing patterns and provide camouflage or warning colors for the insect.
An insect's mouth parts are extremely variable depending on the species, and indicate a lot about its lifestyle. Carnivorous insects generally have either large mandibles to be used in grasping and chewing their prey (e.g. many beetles), or piercing mouthparts used to inject paralyzing toxins into their prey and to suck out the food (e.g. assasin bugs, water boatman, mosquitoes). Butterflies and moths have a long proboscis, which is like a flexible straw, and enables them to sip nectar from flowers and fruit, as well as minerals from moist soil. Some adult insects do not have any functioning mouth parts, and therefore do not feed and only live for a few days, just long enough to mate and lay eggs. For example, many moths in the giant silkmoth family Saturniidae are without mouth parts.