Ant-lions

(Family Myrmeleonidae.)

The so-called ant-lions are interesting creatures which have long attracted the attention of naturalists and of nature students. The average American country boy knows the ant-lion pits in the sand about as well as he knows the curious caddis worms in the brooks. It is rather a large group, and about thirty or more species are known in the United States, three hundred or more comprising the number of described species in the entire world.

The adult flies have short clubbed antennae and four reticulate wings, and are not especially attractive in their personal appearance.

They vary considerably in size, and some of them have a wing expanse of four inches.

The eggs must be laid in the sand, and the larvae when hatched immediately begin to construct little pits. They have flat heads and long jaws, and scrape a load of sand on the head by means of the front legs, and then jerking the head suddenly upwards and backwards throw the sand to a distance. The future pit is planned as to size, and the larva first excavates a circular groove in the way just described. Then it makes another circle within the first and so on until a conical pit results, at the bottom of which the larva remains in hiding. The sand on the sides lies, when the pit is finished, at such an angle that the least disturbance causes it to slide toward the bottom, and when an ant or some other small insect reaches the verge he is apt to slip rapidly toward the open jaws of the larva waiting to receive him at the bottom. In case, however, by great activity, he seems likely to escape over the margin again, his fall is assisted by the ant-lion at the bottom, which throws little showers of sand upwards, and these showers falling upon the struggling insect hasten its descent.

Any little deposit of sand beneath buildings or at the bottom of cliffs along sandy banks in the warm sunshine may be found to contain numbers of these pits. Large collections of them will frequently be found together, which means that one or more females have deposited their eggs in the same general vicinity. The sand must be dry, and hence usually is in a warm, sunny place. When it is damp the larva cannot dig a good pit.

Professor O. Lugger, at a recent meeting of the Entomological Society of Washington, told an interesting story of how a load of sand being carted across a western prairie, far from any stream and miles from any other accumulation of sand, was accidentally spilled through the breaking down of the cart, and how, after a comparatively short time, he found this sand containing many ant-lion pits. This instance indicates that the strong-flying adults are widely distributed and must be in the habit of flying long distances in search of proper places to lay their eggs. There is, of course, also a bare possibility that the eggs were already contained in the sand.

The jaws are enormous and are toothed, and each jaw is grooved deeply on the under side.

After the victim is practically consumed the remains are jerked away by the head just as the sand is jerked up in excavation.

The duration of the life of the ant-lion larva is variable, depending largely upon the abundance of food, just as with some of the other predatory larvae which we have recently mentioned. They are able to undergo long fasts, in which event the transformation may become indefinitely postponed, but when ants and other food are plentiful they reach full growth in comparatively short time, and spin circular cocoons in the sand, making them of silk, to which, since it is gummy when spun, grains of sand adhere. Within the cocoon the larva usually passes the winter.

There is need of careful study of any one of our common ant-lions. The eggs should be described; the number of molts of the larva should be known, and the duration of the different stages under differing circumstances should be determined. It is probable that with most, if not all of the species, there is one generation annually.