The Food Relatioius of the Carabid(ti and Coccinellida'. 47 



captured in tht- orchard so often mentioned took seventy-seven per 

 cent, of their food from the same sources. Tlie individuals from 

 the cabbage field, hovv^ever, show no such excess of animal food 

 as those just mentioned, the ratios standing for them at forty-one 

 per cent. If we seek to account for this sti'iking surplus shown 

 by the second group, we shall find, in the first place, a difference 

 of more than sixteen per cent, between the ratios of insects eaten 

 by the first and second groups respectively — a fact clearly due to 

 the presence of canker-worms whei'e the second group was col- 

 lected. This species was eaten by sixteen of the seventy beetles, 

 and composed about one-fifth of the contents of all the aliment- 

 ary canals. This accounts, however, for only about half the dif- 

 ference noted, the remainder appearing in the larger ratios of the 

 other insects, of mollusks, of earth-worms, and of undetermined 

 animal food. 



This indicates either that other forms of animal life than the 

 canker-worms were superabundant in the orchard, or else that the 

 miscellaneous collections do not correctly represent the ordinary 

 food of the Carabidi\i. The truth probably lies between the two. 

 The extraordinary wetness of the season, together with the amount 

 of rubbish on the ground in the orchard, gave these beetles an 

 unusual opportunity to capture slugs and earth-worms, and 

 afforded excellent harborage for all sorts of insects. On the 

 other hand, many of the beetles from other situations were pre- 

 served especially for dissection because the circumstances of their 

 capture made it seem probable that they were feeding upon veg- 

 etation. 



These tables indicate one interesting and important fact with 

 regard to the preferences of this family, namely, that where an 

 extraordinary abundance of any kind of animal food appeared, 

 with a consequent increase in the percentage of that kind appro- 

 priated by the beetles, this increase was compensated, not by a 

 decrease in the other animal elements, but in the ratios of vege- 

 tation only — a fact which clearly shows that the preferences of 

 the Carabidae are for animal food. It should be noticed, however, 

 that this argument does not apply to all the genera, as is seen, 

 for example, by recalling the record of Anisodactylus. The ten 

 specimens of this genus taken in the orchard had eaten mvich 

 more vegetation than the nineteen from various other places. 



