6 
BULLETIN 1336, U. S. DEPARTMENT OP AGRICULTURE 
Third instar. — Length 8 to 11 millimeters, head width 0.635 to 0.753 milli- 
meter. Abdomen tapering slightly to caudal extremity, with constrictions 
between segments moderately deep. Prolegs on fourth, fifth, and last abdominal 
segments functional. At the second molt the vestigial prolegs on the third 
abdominal segment entirely disappear. Body chitinizations more elevated than 
in previous instar, otherwise the same. Setae for the most part long and black. 
Body shiny yellowish-green, dorsal vessel darker green, accentuated by a faintly 
whitish-mottled border, a narrow mottled whitish stripe on a line just outside 
the posterior dorsal chitinizations, and another through the spiracles. These 
white stripes are not found on all larvae in tlys instar, as individuals vary in this 
respect. 
Fourth instar. — Length 11 to 19 millimeters, head width 0.886 to 1.166 milli- 
meters. Body tapering gradually from sixth to caudal segments, moderately 
constricted between segments. Body shiny yellowish-green, with dark green 
middorsal line bordered on each side by a mottled whitish line, the narrow 
subdorsal stripe along the outside margin of posterior dorsal chitinizations more 
distinct than in preceding instar, and the lateral stripe on a line with spiracles 
wider, and more distinct than the others. Spiracles appearing as small white 
dots, those on prothorax larger and showing a fine dark edge. 
Fifth instar. — Length 16 to 23 millimeters, 
head width 1.306 to 1.586 millimeters. Body 
widest along first three abdominal segments, 
tapering slightly toward each extremity. Con- 
strictions between segments less pronounced 
than in previous instars, and the three pairs of 
longitudinal white stripes more distinct, though 
varying with individuals, head and body other- 
wise the same. Setae for the most part moder- 
ately long and dark. Spiracles small, oval, 
white, with dark edges. 
Sixth instar. — Length 18 to 31 millimeters, 
head width 1.866 to 2.052 millimeters. Body 
with first four abdominal segments nearly 
uniform in width, thence tapering gradually 
toward each extremity. Constrictions between 
segments slight. Prolegs functional on fourth, fifth, sixth, 
and last abdominal segments, pedal hooks 17 to 24. Head 
(fig. 6) subspherical, flattened, oblique, with emargination 
at vertex moderately deep; pale yello wish-green, tips of 
mandibles dark, ocelli black, labrum and outer edge of 
mandibles distinctly whitish ; face sparsely setose with a con- 
spicuously long seta near middle of each side of epicranium. 
Mandible (fig. 7) short and stout, with three distal teeth 
and one broad cutting projection on inside. Cervical shield 
with convexity caudad, bearing four long, dark setae inclined 
cephalad along cephalic margin and four smaller ones along FlG 
caudal margin (fig. 8, TI, la, lb, 2a, 2b). Prothoracic spiracle 
near caudal margin of segment, oval, white, with dark edge, 
Fig. 
-Dorsal view of head of larva of 
green clover worm 
Mandible of larva 
of green clover worm 
Til AlVf-Y^ A VIII A IX 
Fig. 8.— Setal maps of first and second thoracic and fourth, eighth, and ninth abdominal segments of larva 
ofgreen clover worm: TI, Prothorax; Til, mesothorax; A IV, fourth abdominal segment; A VI11, eighth 
abdominal segment; AIX, ninth abdominal segment 
