1914] Richardson—Comments on Warning Colors and Mimicry in Insects 137 
dant. Examination of the stomach contents of a number of these 
lizards showed that their normal food was composed of various 
insects and bits of tender plant foliage. I was however, quite 
surprised to find in the stomach of one adult male, shot at Derby, 
Nev., two wasps so conspicuously banded as to place them un- 
mistakably in the category of insects possessing warning colors. 
One had black and yellow bands on the thorax and abdomen, the 
other black and gray-white bands on the abdomen. Another 
wasp in a partially disintegrated condition, one insect larva, other 
insect fragments, a number of green leaves and a few pebbles fur- 
nished the bulk of the stomach ingredients. The whole mass of 
food had begun to decompose and the colors of the insects were 
considerably dimmed. It is evident here that a mature lizard 
(with full adult colors and testes enlarged) did not discriminate 
between conspicuously banded stinging insects and a harmless 
white larva. As further evidence that Callisaurus shows no aver- 
sion to bright colors, I may add that small, vivid purple flowers 
were found in the stomach of one individual. Merriam! states 
that blossoms form a considerable part of the food of this species 
and although he does not give the colors of the blossoms, it is fair 
to assume that a comparatively large number are brilliantly col- 
ored, as brilliantly colored flowers grow abundantly throughout 
the habitat of Callisaurus. 
At Tallac, Lake Tahoe, Cal., I watched a large adult leopard 
frog (Rana pipiens), on one occasion for a considerable length of 
time. I was concealed so that I could observe the actions of the 
frog, yet it could not see me. In the course of its wanderings over 
a grassy meadow, the frog captured an insect which was taken 
into its mouth, ejected, taken into its mouth again and finally 
discarded. The insect proved to be a drone fly, closely resembling 
certain species in the Syrphid genus, Eristalis. The first abdom- 
inal segment of the fly bore two conspicuous yellow triangular- 
shaped markings, the apices of which did not quite meet 
mediodorsally. Here, then, we have a mimicking insect whose 
form and vivid color pattern combined were not of sufficient 
warning significance to ward off an insectivorous enemy. Just 
why the frog refused to eat the fly is not quite clear, possibly it 
was distasteful, but it is certain that the fly was mutilated beyond 
recovery. 
1N. A. Fauna No. 7, 1893, p. 172. 
