Scorpionflies and Hangingflies: Mecoptera

Mecopterans measure 0.08 to 0.86 inches (2 to 22 millimeters) in length. They are small to medium sized insects that vary considerably in shape. The common name "scorpionfly" refers to male mecopterans with swollen, stinger-like reproductive organs on the tip of their abdomens. These organs are sometimes held over the back just like a scorpion. However, scorpionflies are unable to sting. Hangingflies have long slender bodies and resemble crane flies with four slender wings. Other species known as earwigflies are flat with finely veined wings. Their abdomens are tipped with long pincher-like projections. Snow scorpionflies are small insects measuring only 0.08 to 0.29 inches (2 to 7.4 millimeters) long. The males use their slender, hook-like wings to grasp the nearly wingless females while mating.

Most mecopterans have downward projecting beaks with chewing mouthparts at the tip. The antennae are long and threadlike. They have both compound eyes, or eyes with multiple lenses, and simple eyes, or eyes with only one lens. The four narrow wings, if present, are clear and often banded, spotted, or have darkened patterns along the veins. The forewings and hind wings are similar in size and appearance. In some species the wings are either very narrow, almost as wide as they are long, very short, or absent. All mecopterans have relatively long and slender legs. Unable to support themselves with their thin legs, hangingflies prefer to hang from twigs and leaves by their front legs. The abdomen has nine visible segments and is usually slender and narrow toward the rear. Male abdomens are sometimes tipped with special reproductive organs or claspers.

The larvae (LAR-vee), or young, do not resemble the adults at all. There are three distinctive body types. Many resemble caterpillars and have distinct heads with downward projecting mouthparts and eight pairs of fleshy false legs on their abdomens. Others are c-shaped and grub-like, lacking false legs. A few species have slender bodies without false legs. Some species do not have eyes, while others have seven simple eyes on each side of the head. Many other species have compound eyes with 30 or more lenses on each eye. This is unique among insects whose larvae do not resemble the adults, since most others have only simple eyes.

The legs, wings, antennae (an-TEH-nee) or sense organs, and mouthparts of all mecopteran pupae (PYU-pee), the life stage between larvae and adults, are distinct. These appendages are not attached to the pupa along their entire length. The pupae are not enclosed in a cocoon.