INTRODUCTION. 7 



The beetles and borers. — The order Coleoptera comprises about 100,000 

 species of beetles, divided iuto a large number of families. The beetles 

 are easily recoguized by the hard, sheath-like fore wings which pro- 

 tect the hind wings ; their jaws are stout and thick, more or less 

 toothed, and adapted for biting. 



The larvje of beetles are called " grubs." They have been thus 

 characterized in the author's " Guide to the Study of Insects : " 



The larvae, whea active and uot peniiauently inclosed (like the Curculio) iu the 

 substances which form their food, are elongated, flattened, worm-like, with a large 

 head, well developed mouth iiarts, and with three pairs of thoracic feec, either 

 horny or fleshy and retractile, while there is often a single terminal prop-leg on the 

 terminal segment and a lateral horny spine. The larvas of the Ceramhycidce are 

 white, soft, and more or less cylindrical, while those of the Cureidionidte are lootless, 

 or nearly so, and resemble those of the gall-flies, both hymenopterous and dipterous. 



The pupae have free limbs, and are either inclosed in cocoons of earth or, if 

 wood-borers, in rude cocoons of fine chips and dust, united by threads or a viscid 

 matter supplied by the insect. * * * Generally, however, the autennie are folded 

 on each side of the clypeus, and the mandibles, maxilhe, and labial palpi appear as 

 elongated papilhe. The wing-pads being small, are shaped like those of the adult 

 Meloe, and are laid upon the posterior femora, thus exposing the meso- and meta- 

 thorax to view. The tarsal joints lie parallel on each side of the middle line of the 

 body, the hinder pair not reaching to the tips of the abdomen, which ends in a pair 

 of acute, prolonged, forked, incurved, horny hooks, which must aid the pupa in 

 working its way to the surface when about to transform into the beetle. 



Most of the destructive kinds belong to the following families : 



Body of beetle, broad, flat, hard; antennae short, serrated. Larva with head and 



first succeeding segment very broad and flat Buprestidce. 



Body of beetle more or less cylindrical, with very long, slender antennae ; larvae 



called "borers," their bodies cylindrical, usually footless Ceramhycidce. 



Small cylindrical beetles, with no snout, called bark-borers; larvae footless, thick, 



cylindrical, pointed at each end Scolytidw. 



Hard-bodied beetles, called "weevils," with a long beak or snout, with jaws at tne 



end ; larvae grub like, footless, thick and fleshy CurcuUonidw. 



Moths and butterflies. — While a few caterpillars (mostly of the family 

 ^geriadse and the Cossidse) bore into the trunk and branches of trees, 

 the great bulk devour the leaves. Caterpillars are provided with 

 stout, toothed jaws (mandibles) for cutting leaves. They are voracious 

 feeders, as will be seen by the following extract from Mr. L. Trouvelot 

 in Packard's " Guide to the Study of Insects : " 



Caterpillars g. ow very rapidly and consume a great quantity of food. Mr. Trouve- 

 lot gives us the following account of the gastrondmical powers of the Polyphemus 

 caterpillar: " It is astonishing how rapidly the larva grows, and one who has no 

 experience in the matter could hardly believe what an amount of food is devoured 

 by these little creatures. One experiment which I made can give some idea of it. 

 When the young silk-worm hatches out it weighs one-twentieth of a grain ; when 

 ten days old it weighs half a grain, or ten times its original weight; twenty days 

 old it weighs 3 grains, 6r sixty times its original weight; thirty days old it weighs 

 31 grains, or 620 times its original weight; forty days old it weighs 90 grains, or 

 1,800 times its original weight ; fifty-six days old it weighs 207 grains, or 4,140 times 

 its original weight. 



When a worm is thirty days old it will have consumed about 90 grains of food ; but 

 when fifty-six days old it is fully grown and has consumed not less than one hundred 



