Scorpionflies- Mecoptera

 

The slender, beak-faced insects of the order Mecoptera are commonly known as scorpion- flies. The common name for this order is derived from an unusual structural feature displayed by one family of Mecoptera, the Panorpidae, or common scorpionflies. The mates of this family haw long stinger like genitalia that curve upwards from the end of the abdomen and then arch toward the insect's head. These bulbous organs resemble

the stingers of scorpions. Although the term scorpionfly is often applied to all members of the Mecoptera, only the Panorpidae exhibit this feature.

Before mating, the males of most species of this order have the unusual habit of presenting gifts of food to the females. In some species the male emits saliva, which the females drink voraciously. In others, the male brings a freshly killed insect to the female and the two feed on the animal together. More impetuous than their cousins, the males of the family Boreidae do not bother with these preliminaries.

The head of the scorpionfly is distinguished by large protruding eyes and a long rostrum, or beak. This beak looks something like that of a bird. The mouthparts are designed for chewing and are located at the tip of the beak.

The legs are long, and some scorpionflies are fine jumpers. The long, narrow wings are transparent or marked with patches of pigment. The two pairs of wings are similar in shape, and are so closely fitted that they form an almost uniform membranous surface.

The larvae resemble caterpillars, except that they have more legs. They are equipped with 3 pairs of true legs and 8 pairs of smaller appendages called prolegs. The head of the mecopteran larva is provided with biting mouthparts, and the thorax and abdomen are cylindrical. The larvae are primarily carnivorous, but the adults have a more varied diet. They feed on insect carrion, plant fluids, fruit, the so-called honey- dew of aphids, and live prey.

The females lay only a few eggs-from 12 to 20. In some species the eggs are remarkable in that they are prism- or cube-shaped. Some females lay their eggs in tiny underground cells. Others simply deposit them out in the open, or even drop them while in flight. The larvae are usually found in piles of rotted vegetable material or in moss in damp, wooded environments. The pupal stage occurs in shelters constructed just below the surface of the ground.

Along with the Neuroptera, the Mecoptera share the antiquity record among insects that undergo complete metamorphosis. The Mecoptera include descendants of in- sects that lived more than 200 million years ago. Other mecopteran species, of course, evolved since then.

Fossils discovered in the United States, the Soviet Union, and Australia have led experts to suggest the possibility of a close connection between the Mecoptera and the Diptera, Trichoptera, Lepidoptera, and even the Siphonaptera. Some scholars, in fact, group all of these orders into a single super- order-the Mecopteroidea.

The term Mecoptera is derived from two Greek words: meco, meaning "long" and ptera meaning "wings." The wings of the Mecoptera are indeed long, and marked with intricate patterns of veins and crossveins much like the wings of the Neuroptera. Members of the genus Apterobittacus, how- ever, are wingless.

Panorpidae. This is the largest family of the order Mecoptera and contains the most common species. Known as common, or true, scorpionflies, these insects are usually yellowish-brown in color, with wings spotted

 

 

Despite the dangerous aspect of the stinger-like genitalia of the males, which may be made to look even more dangerous by brilliant red coloration, scorpionflies do not harm human beings.

The Panorpidae are omnivorous, but they feed mainly on dead insects. A few however, are occasional pests. Panorpa communis, for example, has been known to cause serious damage to apple crops.

Two genera of the Panorpidae, Panorpa

and Brachypanorpa, are found in the United States. Living in damp environments in the central and eastern states, Panorpa are usually seen flying in search of carrion in the late summer and fall.

The members of Brachypanorpa are found in the area of the Great Smoky Mountains of North Carolina and Tennessee, and in mountainous regions of Oregon and Montana. They lack the long snout typical of most Mecoptera. The females of this genus have very short wings and are completely incapable of flight.

Bittacidae. Mecoptera of the family Bittacidae hang from branches, leaves, and twigs by their long forelegs, patiently waiting for the passage of flies, aphids, caterpillars, or spiders on which they prey. They are called hanging scorpionflies.

At least one species, Apterobittacus apterus, found in the western United States, has no wings. But these Mecoptera can project themselves into the air, jumping from branch to branch like high-wire acrobats.

Boreidae. The tiny Boreidae, the snow scorpionflies, are excellent jumpers. But their wings are greatly reduced, and they are unable to fly. In the males, the wings resemble slender hooks and are used to grasp the female during copulation. In the females the wings are scale like or absent.

The boreids have long, slender antennae. They closely resemble tiny grasshoppers, except for their long beaks. They are equipped to withstand low temperatures, and are often seen running across snow at considerable speeds. They seem to feed on moss, and are often found in or near mossy places.

Meropeidae. Mecoptera of the family Meropeidae, called earwig scorpionflies, are sometimes seen around lights and under stones. The male's cerci are shaped like forceps and resemble the cerci of the earwig.


 

INDEX : Insects   May 27, 2014 09:09:55 AM