THE BIRD QUESTION. 453 



Pentatoma grisea. And Dr. Shiruer, of Mount Carroll, has obtained a small 

 species of the same family from the striped cucumber beetle, Diahrotica vittata. 

 But these coleopterous and dipterous parasites, though considerably numerous 

 in the aggregate, are relatively small in numbers when compared with the 

 almost countless hosts of hymenopterous parasites, the Ichneumonidge, the 

 Chalcidida?, and the Proctotrupidre ; and from these we have reason to believe 

 that insects in their imago state are for the most part exempt. On the other 

 hand, the subterranean larva? which, in a great measure, are out of the reach 

 of birds, are extensively preyed upon by the numerous kinds of ground bee- 

 tles and their larva^, which occupy the same territory with themselves. 



But the prosecution of this department would carry us too far from our 

 main topic, and we pass on, therefore, to consider another branch of the sub- 

 ject. 



We have stated above that the extensive cultivation of certain fruits and 

 grains has been followed by a very natural consequence, but one which no one 

 probably foresaw, namely, the more than co-extensive increase of some of 

 those species of insects which naturally feed upon them. To such an excess 

 has this multiplication of certain kinds of insects gone, that the production of 

 some of our most valuable crops has been rendered, in some seasons and local- 

 ities, either a partial or a total failure. 



In treating of birds, the interesting question arises whether there have been 

 any similar instances of the excessive increase of the granivorous and frugiv- 

 orous birds. The consideration of this question will bring us directly to the 

 subject of the most immediate practical importance, whether any species of 

 birds are actually found to be so numerous, or so injurious, as to require their 

 destruction, and whether such destruction is, upon the whole, advisable. 



Some birds, like some insects, are remarkably prolific, though why they 

 should be more so than other species, closely related to them, it is impossible 

 for us to tell. There are insects so nearly allied to the potato beetle, and to 

 the chinch bug, that it requires pretty close observation to tell them apart, and 

 yet they are only known as comparatively rare insects. So the wild pigeons 

 sometimes congregate so as to break down the branches of forest trees by their 

 weight; whilst the nearly-related ground-dove is only seen in pairs, here and 

 there, gleaning their subsistence by the road-side. The blackbirds and rice- 

 buntings are also often seen in very large flocks; but the corn and rice crops 

 upon which they depredate are so abundant that these birds do not make any 

 very serious impression upon them. How trifling is the amount of damage 

 caused by these most prolific of birds, when compared with that efiected by 

 some of the more destructive species of noxious insects. Two obvious reasons 

 occur to us why birds do not go on, like insects, increasing almost indefinitely : 

 First, that birds rarely lay more than four or five eggs, whilst insects often lay 

 four or five hundred; and secondly, insects lie dormant through the winter 

 mouths, and require no food, whilst birds have to migrate to different locali- 

 ties, and run all the risks of an insufficient supply of food, when removed 

 from the abundant harvest among which they have been reared. 



But it is more particularly the fruit-eating birds which have excited the 

 apprehensions of the horticulturists, especially those which feed upon the 

 smaller and more delicate fruits, such as cherries, grapes, and the several kinds 

 of berries; a class of fruits which are not usually raised in so great abundance 

 but that the depredations of birds upon them are readily noticed, and some- 

 times seriouslv felt. 



