32 Journal New York Entomological Society. [Voi vi. 
larvae upon which these studies are based were kept in the insectary,, 
and in a temperature varying probably from 6o° to 75° Fah. 
The species is a grass as well as a clover insect, as will be observed 
from the foregoing, and as the striped body of the larvae would indicate, 
but it would seem that the clover leaf is especially desirable as material 
for constructing the cocoon, and it is just possible that the lack of this 
building material would account for the great variation in tastes in select¬ 
ing such as was at hand to supply the place of clover leaves, thus the 
better illustrating natural selection. 
The variation in rapidity of growth I am totally unable to account 
for, as there was an abundance of food, and the larvae were never 
crowded. With the individual variation in size and time required for 
development in the larvae, as well as their difference in coloration, to 
gether with the equally striking difference in the appearance of the 
adult, it would seem that in this case at least individual variation offered 
no very narrow basis for the evolution of forms, which, under a favor¬ 
able environment, might still further progress through varieties to species. 
That this may have actually transpired, is witnessed by the exceedingly 
close resemblance between Drasteria erechtea Cram, and D. crassiuscula 
Haw., either one of which might have given origin to the other, through 
the same course of evolution as that, seemingly, being followed at pres¬ 
ent by varieties agricola G. & R., ochreci Grt., and distincta Neum., the 
two latter being considered by Mr. Slingerland as varieties of D. crassi- 
us cilia. It only requires that these varieties become sterile to each other 
and the parent stock when crossed, in order for them to become species, 
as valid as either of the two just mentioned. 
Explanation of Plates IV and V. 
Fig. 1. 
“ 2. 
“ 3 - 
“ 4 - 
“ 5 - 
“ 6. 
“ 7 - 
« 8 . 
Drasteria erechtea and cocoon. 
<< «< « << 
« «< <« << 
« «« « « 
« << «( << 
« « « « 
Eggs, enlarged (pi. IV). 
Larva, enlarged (pi. V). 
