SUPERFAMILY II. DIVERSICORNIA Antennae generally clubbed or serrate: tarsi 1- to 5-jointed but not heteromerous. Larvae very varied.
This enormous division includes a great number of families and is to be regarded as a provisional group, including all those forms not belonging to other superfam ilies : only a few of the important families can be mentioned here.
The Coccinellidae (fig. 9) or ladybirds are rounded insects with the head con cealed under the thorax : the antennae are feebly clubbed and the tarsi have three evident joints. Most of the species are brightly coloured and spotted, and since both the larvae and adults prey upon aphids and other soft-bodied insects, the family is highly beneficial to man. A small number, however, are injurious to vege tation, especially the squash-ladybird Epi lachna borealis of the United States. More than 2,000 kinds of ladybirds are known and they occur in most parts of the world.
The Dermestidae are hard, dull-coloured insects with scaly or hairy elytra. Their larvae are active, hairy, with evident legs and feed upon dried animal matter, fur, hair, bacon, etc. Certain spe cies have become widely spread through commerce and 16 occur in the British Isles.
The Hydrophilidae (fig. are aquatic or sub-aquatic beetles numbering about i,000 species. They are herbivorous in habit and can be recognized by the very long maxillary palpi which are often mistaken for antennae : the latter organs are very short and termi nate in a hairy club. The large black Hydrophilus piceus when submerged, carries a supply of air beneath the elytra, and lays its eggs in a kind of cocoon attached to a leaf : its larva feeds upon other aquatic organisms.
The Cantharidae (fig. I I) are very soft-bodied elongate insects with long legs and antennae, and include the glow-worms (Lam pyris, etc.) (q.v.) and the so called soldier beetles (Tele phorus). The larvae are mostly carnivorous.
The Buprestidae (fig. 12) are conspicuous metallic insects with short serrate antennae and com prise over 5,000 species. They are essentially tropical and among the most brilliantly coloured of all insects : some species, owing to their splendour and metallic lustre, are used in embroidery and jewellery. The beetles fly ac tively and inhabit forests where their larvae mostly live beneath the bark, wood and roots of trees.
The Elateridae or click beetles are a large and important family of wide distribution. By means of a peg and socket arrangement on the under side of the body, these insects are enabled to leap into the air with a clicking sound, hence their name. The larvae of certain species of Agriotes, and other genera, are known as wire worms (fig. 13) and are exceed ingly destructive to cereals, grasses and root-crops, feeding actively on the underground parts of the plants. Included in this family are the "fire-flies" (Pyro phorus) of tropical America, which emit a bright light from localized areas on the thorax and the base of the abdomen.
Among other families the Anobiidae or "death watch" beetles and the Lyctidae or powder post beetles should be mentioned.