INSECTA 495 



campodeiform to the legless grub, but where a tarsus is present it 

 invariably carries only one claw. 



The Staphylinidae range from carnivorous to phytophagous forms, 

 and, as adults, are characterized by the short elytra which leave the 

 abdomen exposed. The larvae are campodeiform, closely resembling 

 those of ground beetles, e.g. Ocypus (Fig. 342 A). Meloidae or oil 

 beetles also have short elytra but these being wider at the base than 

 is the prothorax are readily distinguished from members of the 

 staphilinid group. The interesting changes undergone by their larvae 

 during metamorphosis have already been mentioned. 



The Chrysomelidae or leaf beetles are exclusively phytophagous. 

 Their bodies are rounded and smooth, and are often high-coloured 

 with a metallic lustre. Antennae of these beetles are filiform and 

 relatively short (e.g. Phyllotreta^ the flea beetle). 



Weevils belonging to the family Curculionidae are easily dis- 

 tinguished by their greatly extended head, forming a rostrum at the 

 end of which mouth parts are borne. Anthonomus grandis the cotton 

 boll weevil of America, and Ceuthorrhynchus the turnip gall weevil, are 

 typical examples. The larvae are apodous. 



The chafer beetles {Scarabceidae), Fig. 342 B, have lamellate 

 antennae. Their legs are often fossorial and bear four-jointed tarsi. 

 Characteristic of these is the fat bodied cruciform larva, almost 

 incapable of movement, and which feeds on roots, e.g. Melolontha 

 (Fig. 318). Aphodius is a dung beetle whose larva develops in the 

 faecal matter of farm animals. 



The family Coccinellidae (ladybirds) is of extreme importance, its 

 members being carnivorous in young and adult stages, aphids and 

 scale insects figuring very largely in their diet. The beetle is smooth 

 and rounded, with head concealed beneath the prothorax. The four- 

 jointed tarsus appears to possess only three joints, owing to the 

 small concealed third joint, e.g. Coccinella of Europe. Novius 

 cardinalis is a classical example of a predatory insect being used in the 

 biological control of the scale-insect, Icerya purchasi, of citrus trees. 



Order HYMENOPTERA (Bees, wasps, ants, sawflies, etc.) 



Mouth parts adapted primarily for biting and often secondarily for 

 sucking as well; two pairs of membranous wings coupled together 

 by booklets fitting into a groove, hind wings smaller; ist segment of 

 the abdomen fused to the thorax, and a constriction behind this 

 segment commonly found; an ovipositor always present, modified 

 for piercing, sawing, or stinging; metamorphosis holometabolous ; 

 larvae generally legless, more rarely cruciform, with thoracic and 

 abdominal legs; pupae exarate, protected generally by a cocoon. 



