Although most slugs are injurious to vegetation, there is one genus which provides flesh-eating slugs that will feed upon other slugs and even worms. The British Ear-shelled Slug (Testacella halotidea), shown at fig. 162, is one of these. It is about 2 1/2 in. long, deep yellow in colour, and may be recognized by a small ear-shaped shell attached to its back, just above the tail. During the daytime it nests in the soil, and is often turned up when digging; but at night-time it roves abroad in search of the common slugs and snails, and makes war upon them. A foreign species, from South Europe (T. Maugei), has become naturalized near Bristol, and may spread throughout the milder parts of the kingdom in time if encouraged. It has a dark-brown body with a larger shell than the native species. Cultivators should become acquainted with these friendly molluscs, and should educate their employees to take care of them.

Caterpillar devoured by the Larvae of Ichneumons, and Caterpillar covered with their Cocoons.

Fig. 160. - Caterpillar devoured by the Larvae of Ichneumons, and Caterpillar covered with their Cocoons.

Lacewing Fly.

Fig. 161. - Lacewing Fly.

1, Chrysopa perla. 2, Eggs. 3, Larva. 4, Larva magnified 5 and 6, Cocoon (natural size and magnified).