52 MASSACnUSETTS AGRICULTURE. 



■whole caterpillar, five or six only would probably have satisfied 

 his appetite. But this is not the general practice of birds tliat 

 devour hairy caterpillars : they eat only an interior morsel, 

 and require a proportionally greater number to satisfy their 

 wants. 



This observation led me to consider how vast an amount of 

 hencdl this single species of birds must contribute to agriculture. 

 We will suppose that each bird spends, at different times during 

 the day, sixty minutes, or one hour, in the aggregate, feasting 

 upon tliis kind of food. This is not an extravagant calculation, 

 since he undoubtedly employs nearly twelve hours of the 

 twenty-four in searching for food, and we may suppose a twelfth 

 part of this time devoted to this description of foraging. At 

 the rate of seventeen per minute, each bird would destroy a 

 little more tlian one thousand caterpillars in the course of each 

 day. We may rationally conclude from this calculation, even if 

 we reduce it to one-half tlie amount, this species of birds must 

 destroy an immense quantity of these vermin during the three 

 or four weeks of the caterpillar season, and that they must serve 

 as a most important check upon their multiplication. 



It it recorded in " Anderson's Recreations," that a curious 

 observer, having discovered a nest of five young jays, remarked 

 that each of these birds, while yet very young, consumed daily 

 at least fifteen full-sized grubs of the May-beetle, and would 

 require many more of a smaller size. The writer makes a 

 calculation founded on the supposition that they would require, 

 of large and small, about twenty each for their daily supply. 

 At this rate, the five birds together would consume 100. 

 Allowing that each of the parents required 50, the family would 

 consume 200 every day; and the whole amount in three 

 months, or one season, to 20,000. The writer, I would remark, 

 commits an error in supposing that the old birds consume more 

 than their young ; whereas they feed upon comparatively few 

 soft insects, or grubs, giving these to their young, while they 

 make their own meals upon the hard and coriaceous insects. 

 The old bird consumes, for example, the beetle, while he feeds 

 his young upon its larva. 



In obedience to a similar instinct, many of the granivorous 

 birds, as the sparrows and finches, while they live chiefly 

 upon seeds, feed their young entirely upon the larva of insects. 



