The Food Relations of the Carabidcp, and CoccineUidrr. 55 



the Coccinellidae themselves, the latter had reached an excessive 

 number, for which the supply of plant-lice was really insufficient, 

 and that for this reason they had resorted to funo-i. 



The chinch-bugs taken l)y the specimens of the second group 

 amounted to only eight per cent, of their entire food, and plant- 

 lice to fourteen per cent., — less than half those taken by the other 

 specimens, whicli stand at thirty-six per cent. The pollen eaten 

 by each group was thirteen per cent., — the same in both. If we 

 combine the two collections, and treat the thirty-nine specimens 

 of both as a whole, we find that insect food is about a third of the 

 entire amount, and that the other animal elements are only trivial. 

 The function of the beetles of this family of limiting the multi- 

 plication of plant-lice is expressed by the fact that these insects 

 compose a fourth of the food of this entire collection. The pollen 

 of grasses and Composit;^ make fourteen per cent., the spores of 

 lichens four per cent., and those of fungi nearly half the whole 

 (forty-five per cent,). The list of genera, as far as recognized, 

 and the relative importance of these, may be found by reference 

 to the tables at the end of this paper. 



Sufficiency of Data. 



The food of the Coccinellidae seems to be, oia the whole, remark- 

 ably simple and uniform, consisting almost wliolly of spores of 

 the lower cryptogams, pollen grains, and plant-lice, and varying 

 but little from one genus to another. This similarity is likewise 

 reflected in the mouth parts, which agree as closely in form and 

 structure as do the ratios of the food. I have consequently little 

 doubt that the data derived from the thirty-nine specimens here 

 discussed, will be found sufficient for a correct general idea of the 

 food of the family under ordinary circumstances. 



With respect to the Carabidai, we have other proof. In the 

 preliminary paper in Bulletin 3 already referred to, based on an 

 examination of only twenty-eight specimens belonging to seven- 

 teen species, the conclusion was announcetl that about one-half of 

 the food of this family consisted of vegetation, and one-third of 

 insects; and the vegetation was thought to be about equally divided 

 between cryptogams, grasses and exogens. If these figures or 

 those of the present paper were far wrong, the probabilities 

 would be very slight indeed that the two estimates would agree, 



