| 
94 BULLETIN 1357, U. S. DEPARTMENT OF AGRICULTURE 
PUPA STAGE ® 
The pupe (fig. 9) at first are whitish throughout. The eyes are dark 
and the mandibles become brown about the middie of the pupation period. 
When the pupa is about three-fourths mature the tips of the metathoracic 
wings become dark gray, following which the mesothoracic wings, which de- 
velop into the elytra of the adult, become somewhat brownish owing to the de- 
velopment of the chitin. When first formed, with the wings still folded close to 
the body, the pupa is from 3.8 to 4.8 millimeters long and 1.9 to 2.1 millimeters 
wide. As it develops the pupa becomes Somewhat shorter and a little stouter, 
approaching the shape of the adult. The head of the pupa is bent down slightly 
and the legs folded against the under side of the body, the metathoracic pair 
being applied against the sides of the abdomen, while the femora of the pro- 
thoracic and mesothoracic pairs project at right angles, with the tibie folded 
up close to the femora. The wing pads are wrapped around the metathoracic 
legs. The antenne are held close to the body and curve under the distal part 
of the femora of the two anterior pairs of legs. The front of the head bears a 
few long sete with bulblike bases; three transverse rows of similar hairs are 
present on the dorsal side of the pro- 
thorax, and the scutellum bears one on 
each anterior corner with a pair on 
either side and slightlyinfront. There 
are six on the upper side of the meta- 
thorax and a row of eight on each ab- 
dominal segment. The last segment of 
the abdomen terminates in two simple 
spines which curve dorsally, Thespines 
are dark in color and become quite 
dark when the pupa is almost mature. 
In front of these hooklike projections 
are two pairs of lateral setze, one on the 
last and the other on the next to the 
last segment, which project backward. 
A strong, curved hook, similar to the 
anal hooks, arises from the posterior in- 
ferior angle of the tibiofemoral articu- 
lation of the metathoracic legs. These 
curve down and in toward the body 
and each bears a long bristle near the 
point. The anterior angles of this joint 
Fig. 9.—Strawberry rootworm. Dorsal bear two long setz with inflated bases, 
view of pupa. Enlarged and similar setze arise from the ante- 
rior angles and the middle of the in- 
ferior margin of the corresponding joints of the other two pairs of legs, which 
do not bear spines, however. The ventral surface of the pupa bears no Set& or 
spines. The abdomen is slightly curved ventrally. 
PUPATION, LCCATION OF PUPA, AND LENGTH OF PUPAL PERIOD 
The full-grown larve hollow out small earthern cells and there 
change to pupe. (Fig. 4.) Most of the pupe collected have been 
found within 2 inches of the soil surface, and when the cells were 
broken into the disturbed pupze would move their abdomens back 
and forth very vigorously with a motion which apparently served 
the purpose of keeping the cavity hollowed out. When sifted soil 
is dropped on a pupa resting in one-half of its cell, the particles are 
swept out of this cavity by three or four movements. 
The duration of the pupal stage was from 5 to 17 days, as indi- 
cated in Table 11, but from 8 to 11 days appeared to be the usual 
time required for this stage. 
——— 
6 The description of the pupa is based on that given by Forbes (13, pp. 152-153), with 
some additions and modifications. 
