Net-Winged Insects and Lacewings

As I write this article, it is a beautiful April morning. All the signs of the arrival of spring fill the air. Birds chirp merrily as they seek their mates and prepare their nests for the arrival of the hungry brood which must be fed. The larger fowl (geese and ducks) are winging their way further north. Not only are the larger creatures of nature becoming more evident but it will also soon be time when we will again be observing the millions of the more minute creatures of God’s Great Universe, as they too begin to make their appearance after their long winter’s rest.

One of the more interesting groups of insects that we will soon begin to observe is a group called Neuroptera. This term Neuroptera means the nerve-winged. These neuropterous insects have two pairs of large, membranous wings which are netted and crisscrossed with many nerve-like veins. The mouth parts are mandibulate, that is they are chewing mouth parts in distinction from the suctorial mouth parts of other insects. Some of the better known insects with suctorial mouth parts are the butterflies, moths, and bees. The antennae of the neuropterous insects are long.

The nerve-winged insects pass through four distinct changes of development and are therefore classified with those insects which have a complete metamorphosis. The four distinct stages are the egg, larva, pupa, and adult.

Among the nerve-winged insects can be found the lacewings (Chrysopidae), the ant lion (Myrmeleonidae), the alder flies (Sialidae), and the remarkable dob- son fly (Corydalidae).

The lace-wing (Chrysopa) is a very common neuropterous insect attracted to lights at night, or it may be taken in great numbers by sweeping the low vegetation in the summer with a collectors net. Members of the beautiful family Chrysopidae are distributed throughout the world and look much alike, wherever they are found. Of some 425 species, only 12 live in the United States. There are fourteen species in Gr. Britain, and few more in Europe. The rest are scattered over this great planet which we call Earth.

All the species have oval-shaped wings, thickly crossed by numerous veins. Although most are green, some are yellow, others are tan, and still others are brown. All are shimmering and transparent, well described by the order’s name of lacewing. The name Chrysopidae comes from the Greek words for “golden” and “eye,” which refers to the golden eyes of the adult, which are large, compound, and set far apart. The name aphis lion refers to the immature, or larva, which feeds upon aphids (plant lice) and other small insects.

In general, all species have the same habits. When the eggs of the adult are ready, the mother poising over a suitable leaf surface exudes a bit of secretion which hardens instantly in the air, to form a fine, hair-like stalk. On top of this stalk, she places one egg; then she makes another stalk for another egg, until there are several eggs on the leaf.

There are two possible explanations for this habit of the mother. The first is that the mother deposits these eggs on a stalk to prevent other insects from eating the eggs, but there seems to be a more fundamental reason for this habit than the one just suggested. The mother seems to realize that the young which shall hatch from these eggs are extremely predacious and that if she laid all of the eggs together on the surface of a twig, the one first hatched would eat up all its potential brothers and sisters. This seems to be quite a logical conclusion because if you ever watch aphis lions in action, you will accept the second theory as being the most plausible. These aphis lions seem to have just one desire in life, and that is to sink their jaws into the first object they meet.

The aphis lion is one of the ferocious of all insects; and as their name suggests, the larvae feed upon plant lice, which they devour by the dozens. They do this by drinking in the juices through grooves inside their jaws. They proceed from aphid to aphid, casting aside the drained bodies when finished. They never stop, or even hesitate until the branch they are on is swept clean.

When full grown, the aphis lion spins a rough cocoon in which it remains until ready to emerge as a winged adult. When handled, the Chrysopidae, both adults and larvae, give off a disagreeable and lasting odor, and for this reason are sometimes called stink flies.

The ant lions “Trappers of Insects” are so named because the larvae of members of this family have odd feeding habits. The eggs are laid on the ground. Unlike the aphis lion, the ant lions when they hatch out do not go out hunting for their prey, but lie in wait at the bottom of a trap constructed in loose, dry sand. Usually these pits are in the shelter of plants or buildings where they are protected from the rain. These traps are planted in the dry areas because should the trap become wet the trap is rendered useless. These traps are constructed by the larva (doodle-bug) who not only is an expert trapper but must also of necessity be an expert engineer. The pit is excavated in a particular fashion, and if an ant lion is placed on a smooth sand area, the digging technique can be observed. The larva backs around in a circle because that is the only way it can walk due to the arrangement of its legs. This is an advantage when it has captured a struggling prey and must pull it beneath the sand. It makes a shallow trench by flipping sand out as particles fall and accumulate on its head. It makes a narrower circle, and then a still smaller one, until a shallow funnel results. It backs down into the center and continues to flip out sand, gradually deepening the pit until a fairly steep funnel is formed about two inches deep. If a small pebble falls in, it is promptly tossed out, but some observers have witnessed the insect’s reaction to a larger pebble; it burrows under the stone and comes up under it, raising the pebble above the sand balanced on the tip of its abdomen. The larva backs up the slope of the pit and deposits the unwanted object on the rim.

Now its trap is ready for some unwary victim to happen into.

When insects run over the sand and fall into the pit, many could escape eventually by scrambling up the loose sand were it not for the efforts of the ant lion to prevent them from doing so. The larva first backs deeper into the sand, then begins to toss up sand in a shower. This falls about the rim of the pit and cascades down, in a virtual avalanche carrying the struggling insect along. When the victim is close to the bottom, the ant lion begins to snap its powerful jaws, and capture is assured. The prey is dragged down under the sand, paralyzed by means of a poisonous fluid which also liquefies its inner tissues, and then is sucked dry. The empty skeleton of the insect is tossed out of the pit later, and the ant lion lies in wait for another victim.

When an ant lion larva is fully grown, it begins to spin a cocoon, and accomplishes the remarkable feat under sand without enclosing any sand particles. The larva then pupates for a month or a little more, after which it emerges as a fully formed flying adult. The mature ant lion does not in any way resemble the stocky larva, but is a delicate insect which bears a general resemblance to the dragon fly or damsel fly although it is entirely unrelated. It is easily distinguished, however, by its short and prominent antennae, which are lacking in damsel flies and dragon flies.