30 



THE PRACTICAL ENTOMOLOGIST. 



rious sorts of mice, the mole, badger, hedgehog, 

 squirrel, fox, and wild swine. Whether the bene- 

 fits derived from them in this way counterbalance 

 the mischief which many of these creatures cause, 

 it is difficult to determine. 



" Birds contribute much more than the mammi- 

 ferous animals to the destruction of injurious insects. 



" Many caterpillars know instinctively how to 

 conceal themselves from the birds which prey on 

 them ; in many their covering of stiif hair acts as a 

 protection against their enemies. Others remain 

 all day between rolled-up or flatly united leaves, 

 and only go out to feed at night. Others find suf- 

 ficient protection in the buds, into which they soon 

 penetrate. Gregarious caterpillars live while they 

 are changing their skin, and when they are going 

 into the pupa state, in webs, in which they are in- 

 accessible to birds. Others live under the bark of 

 trees, arid even deep in the wood. 



" Notwithstanding these and other obstacles, a 

 great number are yearly devoured by the birds, par- 

 ticularly during the breeding season. In winter a 

 multitude of birds, driven by hunger into the vil- 

 lages, diligently search the branches of trees for the 

 eggs of many sorts of moths that are glued to them, 

 and which yield a scanty sustenance to these frugal 

 animals. 



" It is a wonderful provision of nature that ex- 

 actly at the same time that the insects, injurious 

 from their great numbers, appear, the greatest num- 

 ber of the insectivorous birds have hatched their 

 broods, and their voracious young are ready to be 

 fed upon them. 



" Insectivorous birds are also sometimes granivo- 

 rous, and feast readily on our fruit, particularly 

 cherries; but the injury they cause in this respect 

 is not to be compared to the use they are of in de- 

 stroying insects. At least we never hear of univer- 

 sal devastation caused by birds, though we do by 

 insects. 



" From what has been said, it will be sufficiently 

 clear how strongly it should be inculcated by the 

 authorities to forbid the capricious persecution of 

 these useful birds, particularly in the breeding sea- 

 son. 



"Among amphibious animals, which destroy in- 

 sects, lizards hold a conspicuous place. Grasshop- 

 pers are the favorite food of many species. Frogs 

 and toads also devour many insects. 



" Besides mammalia, birds, and amphibious ani- 

 mals, nature, to restore the equilibrium among her 

 Creatures, and particularly to prevent the prepon- 

 derance of some sorts of insects, makes use chiefly 

 of insects themselves, namely those which feed upon 

 others, and which by degrees obtain a superiority 

 over those that are hurtful to us. 



" Thus, many .sorts of beetles, particularly of the 

 family of ground beetles ( Caralldse), destroy a mul- 

 titude of the pupas of moths lyitig in the earth. 

 Many flies, allied to our house fly, but much larger, 

 lay their eggs in living caterpillars aud destroy 

 them. But the most useful are the Ichneumonidae. 

 The females of this numerous family, 1300 species 



of which Professor Gravenhorst has described in 

 Europe alone, lay their eggs entirely in the bodies 

 of other insects. 



" The manner in which these Ichneumonidae ac- 

 complish their work of destruction is highly curious 

 and interesting, All the species are furnished at 

 the end of the body with an ovipositor, composed 

 of several bristles attached together, with which 

 they pierce the larv£B of other insects, and introduce 

 their eggs into the flesh of the wounded animals. In 

 some this sting is longer than the whole body, some- 

 times more than an inch long, namely, in those spe- 

 cies which seek the object of their persecution in 

 the interior of trees or wood that has been much 

 and deeply perforated by the insects which reside 

 therein. They perceive, either by their sense of 

 smelling or by their antennae, that their prey is at 

 hand, and introduce their eggs, not without diffi- 

 culty, into the bodies of thfe larvae living in the 

 wood. vSome attack caterpillars feeding openly on 

 plants, others perforate the various excrescences, or 

 gall-nuts, which also contain larvae; there are even 

 many species, scarcely visible to the naked eye, 

 which lay their eggs in the eggs of other insects, 

 such as butterflies, and thus anticipate their destruc- 

 tion. 



" The eggs are hatched within the body of the 

 living insect, and the young parasites, in the most 

 literal sense, fatten on the entrails of their prey. 

 At last the wounded caterpillar sinks, the enemies 

 escape through the skin, and become pupse; or the 

 caterpillar, notwithstanding its internal parasites, 

 enters the pupa state, but instead of a butterfly, one 

 or more Ichneumonidae appear. To these wonder- 

 ful animals we often owe the preservation of our 

 orchards, woods and grain. 



" Besides the above-mentioned Ichneumonidae, 

 ants, field or tree bugs, and many sorts of spiders, 

 contribute greatly in extirpating various insects. 



" 2. Means which the human understand- 

 ing C.VNOPPOSETOTHEDEVASTAXIONSOrlNSECTS. 



— Previous to taking any steps for the destruction of 

 injurious insects, it is indispensably necessary that 

 we should be perfectly acquainted with them and 

 their economy, not only in their perfect state, but 

 in all their difierent stages. For it might easily 

 happen that we might destroy those most beneficial 

 to our fruit and forest trees, and suffer their enemies 

 to remain. I will give a single instance as an ex- 

 ample. Entire heaps of small cocoons are seen on 

 the bark of trees, often not larger than the eggs of 

 many butterflies. The gardener or forester who 

 does not know that these are the cocoons of the 

 useful Ichneumonidae, but considers them to be 

 really the eggs of moths, rubs them oif the tree, and 

 thus annihilates his best friends. To people unac- 

 quainted with the economy of injurious insects, the 

 choice of the means necessary for their destruction 

 is perplexing. It is often impossible to take mea- 

 sures against the perfect insect, because it either 

 withdraws itself from our observation, or lives in 

 concealed corners, or only appears by night. We 

 must, therefore, try to find where it lays its eggs, 

 and whether anything can be effected against them. 



