THE GRAPE-LEAF SKELETONIZER. 81 
mm. and the minimum 0.316 mm. The average size of the egg is 
0.566 mm. by 0.349 mm. 
The eggs are deposited on the underside of the leaves in clusters, 
and from 12 clusters counted, ' 
the minimum contained 7 eggs, 
the maximum 260, the average 
cluster containing 107.9 eggs. 
Observations on 1,035 eggs 
gave the average length for 
the egg stage as 7.92 days, 
with a maximum of 9 days 
and a minimum of 7 days, the 
average mean temperature for 
the period of incubation of the 
various eggs being 77.5° F., 
with cloudy weather prevail- 
ANY NAN} 
X\\ in a 
aw 
A Fie, 13.—The grape-leaf skeletonizer (Harri- 
Ing. The eggs under observa- sina americana) : a, Egg, greatly enlarged ; 
b, cluster of eggs in natural position on 
tion were from the second Rs 
leaf. (Original. ) 
generation of moths, and the 
length of the stage would probably be somewhat greater for the first 
generation on account of lower temperature. 
LARVA. 
First instar.—Body yellowish-white, translucent. Head similar in 
color to body, retractile, broader than body, which gradually tapers. 
Segments 2-13 with a transverse median row of spinelike bristles, 
about 0.2 mm. in length, extending to venter on each side; whitish 
when viewed under a 34-inch objective, but the dark-colored joints 
cause them to appear blackish under a small magnification. Thoracic 
feet small, pointed, color similar to body; abdominal feet small, 
visible only as small wartlike protuberances. Length, 1-1.25 mm.; 
width of head, 0.18-0.25 mm. (variable). 
Second instar.—Body dilute-yellow, head retractile, darker, eyes 
and mandibles dark brown. Tubercular areas now distinct under a 
%-inch objective as a transverse row of wartlike clusters of whitish, 
segmented bristles about 0.2 mm. in length, with apex, joints, and 
bulb at base of the bristles black. All the segments laterally, and 
dorsum of the anterior and posterior segments with long, whitish. 
segmented hairs about 0.75 mm. in length. Thoracic feet small, 
pointed, dilute-brownish; abdominal feet, more distinct now, appear- 
ing as small stumplike projections. Length, 1.666-2 mm.; width of 
head, 0.283-0.333 mm. 
Third instar.—Body orange-yellow, head retractile, dilute-brown, 
eyes and mandibles brownish-black. Segments 2-13 show wartlike 
