Tipulidae
A family of two-winged flies (Diptera) distinguished by the long, slender body, with long, unarmed legs, and long, rather narrow wings, with many veins There is a distinct furrow on the back of the thorax, between its front and middle segments. The head is usually rather small and round, and bears rather long antennae, which have from six to nineteen joints. One of the commonest species, the Common Crane Fly (Tipula oleracea), is shown, of the natural size, at. Fig. 42. The larvae of Tipulidae are popularly known as "grubs," and under that name are but too well known to farmers, as they are among the worst enemies of the cultivated crops, and of pastures. They are dirty-grey, cylindrical maggots, with no distinct head or feet. The rings are separated by shallow grooves. The body is blunt behind, but bears six small, fleshy tubercles on the blunt end. The "grubs" are clumsy creatures, and move slowly, but are protected from injury by their tough skin, which has procured them the name of "Leather-jackets" in some localities. They are of various sizes, when full grown, as there are numerous species. The larvae of T. oleracea reach a length of over 1in., with a thickness of about 1/5in. They live in the soil, a little way below the surface, feeding on the roots of grasses and other plants. When numerous, they not unfrequently destroy the grasses on lawns, or devour great part of the garden and field crops. The produce of damp soil is peculiarly apt to suffer from their ravages. When full fed, they change into pupae, which are of nearly the same size as the larvae, but are provided with cases on the front part of the body for the wings and legs of the future Crane Fly. The rings of the abdomen of the pupae each bear a transverse row of short, stiff spines; and, by means of these, the pupae can wriggle partly out of the soil, just before the flies are ready to break out, to permit their more easy exit. There are many species of Tipula, but there is no need to describe them in detail, as all show much the same habits, and must be combated by the same methods.
Treatment. The female flies are prevented from laying eggs, and the larvae may be destroyed, by the employment of dressings of such materials as gas lime or soaper's ashes. Common salt has also been found useful, in the proportion of about half a ton to the acre, just before the ground is ploughed. Deep ploughing is very beneficial. To enable the crops to resist attacks, the most effectual method is to stimulate growth by dressings of guano or other manures, so as to render the plants less liable to serious injury, even if partially eaten. The use of heavy rollers has been recommended for lawns, and this would probably kill those grubs that lie close to the surface; but they are not very liable to injury from pressure, unless it is very considerable.
Traps, as recommended under Crane Fly, consisting of slices of turnip, potato, or other fleshy roots or tubers, may be employed with success for the protection of choice plants or crops. They should be sunk a few inches below the surface of the soil, and be examined every two or three days, the grubs found in them being removed and destroyed.
Certain birds, especially starlings and rooks, are very useful in reducing the number of grubs, of which they eat multitudes; they ought, therefore, to be encouraged. Among the most productive breeding-grounds of grubs (as well as of other pests of gardening and of agriculture) are uncultivated corners or edges of shrubberies and fields, where weeds are allowed to grow unchecked from year to year. It is advisable to get rid, as thoroughly as possible, of such sources of trouble.