The Fond of Birds. 99 



for permanent preservation, These larva? were tilled with 

 vegetation, some of which was recognized as the leaves 

 and rootlets of the grass-like weeds of the vicinity, while 

 the remainder evidently consisted of the leaves of net- 

 veined plants, probably trees, by which the ground was 

 overshadowed. The frequency with which these tissues 

 w^ere found penetrated l)y fungi showed that this vegeta- 

 tion was in a decaying condition. I next looked through 

 my notes of the contents of the stomachs of meadow-larks 

 shot at the very time when the robins were stuffing them- 

 selves with this Bibio larva, and found that the meadows- 

 larks had not eaten so much as one. As they search the 

 ground more closely than the robin, relying almost as fully 

 on insect food, this seemed good evidence that the larva 

 occurs here chiefly in situations frequented by the robin 

 and not by the meadow-lark, — that is, in gardens, groves 

 and the like. It was only in such situations that I was 

 al)le to find it myself. There is, therefore, no present ev- 

 idence that this larva is now injurious even in the slight- 

 est degree, and the robin is not entitled to any very posi- 

 tive credit for its destruction. There is some probability, 

 however, that if the insect were allowed to increase indefi- 

 nitely, it w^o.uld become injurious to living vegetation ; 

 and if so, the high rate of its multiplication would make 

 it a seriously destructive pest. The immense numbers 

 annually destroyed by the robin may be inferred from the 

 fact that I have counted as many as one hundred and sev- 

 enty-five from the stomach of a single bird ; and as fully 

 half of the food of the robin for a month consists only of 

 this insect, fifty larvae a day for each robin, or one thou- 

 sand five hundred for the month, will be a very moderate 

 estimate. 



About five per cent, of the food of February consisted 

 of beneficial insects. 



Ma r G h . 



Nine birds were shot on four different days of March, 

 between the 9th and 31st, six of them in McLean county, 

 and three at Galena. Four of these had eaten Bibio larvae 

 again, w^hich amounted to thirty-seven per cent, of the 



