Some of Nature's Methods of Subduing Injurious Insects. 179 



•whether affecting fruit or field crops, their future, whether "to be, or not to 

 be," has been left to be settled mainly by the controlling forces of nature. 



Among the chief agencies employed by nat.ure in subduing injurious in- 

 sects are other species of insects, known generally as friendly insects. These 

 insect friends may be divided into two classes, namely, predatory and para- 

 sitic species. Among the former we have what may be regarded as the car- 

 nivora among insects — the lions and tigers of the insectivorous world, who, 

 fleet and powerful, roam about, "seeking whom they may devour." Fore- 

 most among these are the ground-beetles, or Carabidw, a large family, con- 

 sisting of many genera, embracing several hundreds of species, most of whom 

 live largely or entirely on other insects. Some of the larger form.s, such as 

 the copper-spotted calosoma, Calasoma calidum, and the green caterpillar- 

 hunter, Calosoma scrutator, are commonly known as caterpillar-hunters, for 

 the reason that they usually pursue their useful avocation in open daylight, 

 and, being of large size, their proceedings are easily observed. These species 

 are quick in their movements, seizing their prey with relentless zeal, and 

 devouring them with great rapidity. Another useful group is known under 

 the name of tiger-beetles, Cincindelida-, a race remarkably active in their 

 movements, and possessing keen powers of vision, which enable them quickly 

 to discover the objects of their search. The lady-birds also, CoccineUidoe,we\\ 

 deserve mention here, for they not only devour small insects, but also feed 

 largely on the eggs of other insects. A large proportion of the useful insects 

 thus far referred to devour other insects, both in the larval and perfect con- 

 dition. 



But man's insect friends are not confined to the beetle tribes. Among the 

 Hemiptera, or true bugs, there are loyal and true species, which attack man's 

 enemies with vigor, and suck their blood to the last drop. The observant 

 eye will occasionally detect these creatures in their useful mission, with their 

 extended spear-like proboscis thrust into the side of a caterpillar, quietly re- 

 ducing it to a shriveled skin ; or, if the larva attacked shows much activity,, 

 its squirming body is often hoisted aloft in mid-air, and there gradually 

 emptied of its contents. 



Friendly insects are also found among the Neuroptera. The larvae of the 

 lace-wing or golden-eyed flies, Chrysopa, are very active and useful creatures, 

 and devour immense numbers of aphides. Their formidable jaws are tabu- 

 lar, and are furnished with a bulb-like base, by the alternate expansion and 

 contraction of which the soft bodies of the insects they feed on are rapidly 

 emptied of their contents. Some of the tiniest mites, which are scarcely 

 visible to the unaided eye, also render us great service b)' feeding on the eggs 

 of injurious insects. The egg-clusters of the tent caterpillar, Clisiocampa 

 Americana, are very liable to be either partially- or wholly destroyed by this- 

 means. 



Among the Hyme/ioptera, or four-winged flies, man has many friendly 

 helpers. Many species of wasps, which construct cells for their young to- 

 live in, store these cells with various insects, both in the larval and perfect 



