4 FARMERS’ BULLETIN 668. 
growth four or more weeks later. This period will undoubtedly 
vary in different temperatures, according to the season of the year 
when oviposition takes place. 
Eggs are shown a little larger than natural at ¢ of figure 1, and 
much magnified at @ and 6 of figure 2, ¢ showing the sculpture. 
THE LARVA. 
The larva is a soft, whitish, grublike caterpillar of nearly cylin- 
drical form, with a small dark head and a few very sparse hairs on 
each segment. Larve in the earlier stages of growth are illustrated 
by d, e, and f of figure 2. A full-grown larva is shown in profile 
within an open stem at figure 1, d, and the head and first two tho- 
racic segments appear in figure 2 at g. Mature larve measure about 
an inch (25 mm.) in length. 
In the District of Colum- 
bia full-grown larve, as 
already observed, occur as 
early as July 16; in New 
Jersey, later in July, and 
are to be found upon the 
vines in different stages in 
October; at Washington, 
as late as the second week 
of November. 
Fic. 2.—Squash-vine borer: a, Egg as seen from above; b, After attaining maturity 
same from the side, showing sculpture; c, sculpture of egg the larvee desert the stems 
greatly enlarged; d, newly hatched larva; e, half-grown 
larva; f, head of same from side; g, head of mature larva and enter the earth, bury- 
from above. a, b, and ¢, Much enlarged; d, ¢e,f,and g, less ing themselves to the depth 
enlarged. (Author’s illustration.) : 
of 1 or 2 inches, and form 
their cocoons, in which they transform to pupx. The cocoon (fig. 1,f) 
is constructed of silk and coated externally with fine particles of earth, 
which adhere on account of some gummy secretion of the larva. 
THE PUPA. 
The pupa, or chrysalis (shown in profile at e, fig. 1), measures about 
inch (16mm.) inlength. Itisshiningmahogany brown in color, and 
its head is ornamented in front just above and between the eyes 
with a hornlike process. By means of this the pupa cuts its way 
out of one end of its cocoon and by the aid of the abdominal hook- 
like spines forces itself to the surface of the earth before transform- 
ing to adult. 
NUMBER OF GENERATIONS. 
The question of the number of generations produced annually in 
localities of different temperatures which this insect inhabits has 
been solved by actual observation, the results serving to indicate 
that it is practically single-brooded on Long Island and northward; 
that there is a tendency to two broods in New Jersey, the moths in 
te 
