ANIMAL PESTS OF PLANTS 171 



Life- History of a Beetle. 



Many destructive agricultural pests belong to another 

 order of insects, the beetles. These go through a similar 

 series of changes: egg, larva (called " grub" m this 

 order), chrysalis or pupa up to the perfect insect. The 

 larvae of beetles are often provided with three pairs of 

 jointed legs, but have no sucker-feet. Sometimes they 

 are entirely without legs, and are then usually white and 

 fleshy. They have very strong biting jaws, and the 

 segments of the body are not so well marked as in 

 caterpillars. 



The pupae are inactive, often enclosed in a cocoon, 

 and in them the form of the forthcoming beetle is easily 

 recognised. 



The perfect insect is usually hard, with two pairs 

 of wings, of which the first pair are hard and long, 

 forming a sheath for the second pair, which are thin and 

 membranous. Their jaws are usually strong and well 

 adapted to biting. 



Beetles thus prove destructive both in the larval 

 and in the mature stage ; they feed upon a great variety 

 of substances. Some, like the grubs of the flea-beetles, 

 burrow in the leaves of plants ; others eat the roots 

 underground for instance, wire-worms, the grubs of 

 cockchafers, and of daddy longlegs or " leather jackets." 

 The death-watch beetle bores into beams in houses, and 

 several others eat their way into the stems of trees ; and 

 the ravages of a little beetle, the so-called "furniture 

 worm," in furniture are well known. Biscuits, grain, and 

 other stored food-stuffs, are very liable to the attack of 



