﻿164 Journal New York Ent, Soc. [voi. hi. 



The fact that several species of this genus are literally swarming over 

 large areas of country, and their habits are such as to expose them al- 

 most continually during the adult stage to attacks of birds, while in all 

 of the investigations of the food of birds they rarely appear, has raised 

 the question of their being inedible. The colors of our commonest 

 species are black, black and yellow, and green. It is true that a ma- 

 jority of the blossoms frequented by these beetles are more or less of a 

 yellow color, but the black stripes and spots on some species and the 

 almost entire black of others rather leads to the inference that black is 

 in this case a warning and not a protective color. Or, in other words, 

 while the colors of some of our species might be supposed to be protec- 

 tive, their coloration appears to be so only so far as warning colors can 

 be said to constitute protection. The color of D. longicornis, being as 

 it is of a uniform green color, or at most but slightly tinged with yel- 

 low, would form a protection, provided it fed upon foliage of the same 

 color — but it does not ; and its green color only makes it the more con- 

 spicuous on the purple bloom of the thistle, or the yellow flowers of the 

 Solidago. If i2-piinctata, soror or tricincta habitually fed upon a yel- 

 low background like, for instance, the rays of the flowers of Helian- 

 thus, and should puncture them with small holes that would at a short 

 distance resemble small black spots, then these species might be sup- 

 posed to gain protection from their coleration. But neither these or 

 longicornis are seemingly in the least protected by their coloration, and 

 their immunity from attacks of birds must be due to other influences. 

 Bates, in his " Naturalist on the River Amazon," states that in the for- 

 ests along the Amazons "the Eumolopidse and Galerucid^e were much 

 more numerous than the Chlamydes and Lamprosomas, although being 

 also leaf eaters and having neither the disguised appearance of the one 

 or the hard integuments of the other ; but many of them secrete a foul 

 liquor when handled, which may perhaps serve the same purpose of 

 passive defence." It is here that without doubt we shall find the secret 

 of the protection of species of Diabrotica against the attacks of birds. 

 Perhaps the most convincing evidence on this point is to be found in a 

 paper by Mr. Charles J. Gahan, in Trans. Ent. Soc. Lond. 1891, pp. 

 367-374, plate XVII, in which, under the title of "Mimetic resemb- 

 lances between species of the Coleopterous genera Lema and Diabro- 

 tica^' seventeen species of the former genus, inhabiting South and Cen- 

 tral America and Mexico, shows a remarkably close resemblance to 

 nearly an equal number of species of the latter genus inhabiting the 

 same regions. In the colored plate which accompanies this paper illus- 



