10 
BULLETIN 427, U. S. DEPARTMENT OF AGRICULTURE. 
THE FULL-GROWN LARVA. 
The full-grown larva? (fig. 7, left and right) are slightly fusiform in 
shape, and plainly constricted at the segments. 
The head is dark brown, with the exception of the frons, which is 
lighter in color. The cervical plate is black, with a pale narrow me- 
dian line, and the thoracic 
legs are black. The venter 
and sides of the abdominal 
segments are a waxy white 
and the dorsum is gener- 
ally a light pink, though in 
some larvae there is enough 
green present to give the 
dorsum a very light green- 
ish tinge. The spiracles are 
small, dark, and inconspicu- 
ous. There are about 10 
to 14 small light hairs on 
each segment, at the base 
of each of which there is a 
small black spot. There 
are fire pairs of prolegs, 
and near the base of each, 
on the outside, is a small black projection armed with three stout, 
short, black hairs. The anal plate varies from a yellow to dusky 
yellow in color. The full- 
grown larva is from 9.5 to 
11.5 mm. in length, and 
when fully extended is 
even slightly longer. At 
the widest point the aver- 
age is about 1.5 mm. in 
width. 
As pupation approaches 
the entire larva becomes 
greenish in color, and 
much shorter. 
THE PUPA. 
When first formed the 
pupa (fig. 7, center; fig. S) 
is white, with green mark- 
ings, but soon changes to deep uniform brown. In general form it 
is spindle-shaped, being broadly rounded at the head, widest at the 
thorax, and tapering evenly to the last abdominal segment. The 
Fig. 6. — Egg masses of the tuber moth on the surface of a 
potato. Enlarged. (Original.) 
Fig. 7. — The potato tuber moth: Ventral view of larva at 
left: dorsal view at right ; pupa in middle. Larva much 
enlarged; pupa still more enlarged. (Original.) 
