You may have never seen a mecopteran, such as a scorpionfly or a hangingfly, because the adults are so secretive. They hide out in dark, shaded woodlands. They don't fly much, spending most of their time sitting on leaves. Mating tends to occur at night. Mecopterans actually live all over the world, even in polar habitats. They prefer moist, shady conditions, like what you find in dense forests. Females lay eggs under damp leaves or soil on the forest floor, and the larvae develop in the dark hiding places. In polar areas, larvae may develop in clumps of moss surrounded by snow. Mecopterans are closely related to fleas and flies. But, mecopterans are larger, often with long, clear wings patterned with dark veins. Their heads are long too, narrowing down to where their mouthparts (mandibles) attach. Despite the sinister appearance created by their long, thin faces, they do not bite or sting.

Insects are the only animals without backbones (invertebrates) that can fly. Wings of insects are flat and paper-thin, supported by a network of veins. They flap their wings at incredible rates, up to about two hundred times per second. Most insects have two sets of wings that work in tandem because they are coupled by a fold, a hook, or other structure that catches the back wing as the front wing beats. Wings are made of two layers of cuticle for strength. The front wing is often hardened to serve as a protective cover, leaving the back wing to provide most of the flying power. Many insects walk around instead of, or in addition to, flying. The good walkers tend to touch three legs to the ground at a time, alternating with other sets of three (tripedal gait). The stable triangles formed by the legs allows them to move quickly without falling over. Some insects "walk" on water or swim.