No one, who is acquainted with the _Aphides_, and the various insects which prey upon them, will ever permit a valuable plant to suffer injury from these pests. He will collect some of the _Aphis'_ enemies alive, carry them to the affected plant, and set them free to do their work; there they will remain while the food lasts. The _Aphides_ have more numerous, more active, and more inveterate enemies than insects of any other group--these are the means by which their wonderful fecundity is kept in check. Among them are the Aphis-lions, which are the larvæ of the Golden-eyed and Lace-wing flies, belonging to the order _Neuroptera_. They are reddish-brown, with a dark stripe down the middle, and a cream-colored one on each side; bodies long, narrow, and wrinkled transversely. Their jaws are long, curved like sickles, projecting forward from their heads horizontally.[29] The _Coccinellidæ_, mentioned as useful members of the order _Coleoptera_, on a previous page, are among the most active enemies of the _Aphides_. The eggs are laid in clusters of twenty to forty on the under side of a leaf, to which they are closely glued; they are oval, and light yellow. They hatch into small blackish larvæ, which are active, and which boldly attack an _Aphis_ much larger than themselves, leaving only the empty skin. They consume hundreds while in the larval state, about two weeks, when they attach themselves by the tail, and go into the pupa state. One of the largest of these Lady-birds is the _Mysia 15-punctata_; the larva is a clear white, the middle of the back tinged with red, and two or three black spots on each segment--nearly a hundred species of Lady-birds are found in this country. The perfect insect, as well as the larvæ, feed upon _Aphides_, and instead of being destroyed, they should be cherished and encouraged. Besides these, there are other inveterate enemies of the plant-lice in the _Syrphidæ_, which are two-winged flies, resembling the common house-fly, but handsomer. They deposit their eggs where _Aphides_ exist; the maggot, which hatches from these, seizes upon the first _Aphis_ that comes within his reach, and sucks its fluids. A medium-sized worm will consume a hundred lice in an hour. They are always found in a colony of _Aphides_.[30] =Aphis prunifoliæ=, or the Plum Leaf-louse, is black, with pale green abdomen. It is found on the under side of the leaves, which become wrinkled and distorted. It is not so abundant as some other species, but its habits are similar.[31]