8 BULLETIN 1426, U. 8. DEPARTMENT OF AGRICULTURE 
median triangular area, truncate, or faintly emarginate. Clypeus 
with raised W-like rugosity with corresponding lateral and anterior 
mesial concavities; anterior margin truncate or obscurely broadly 
emarginate. Mature head capsules in pupation chambers vary greatly 
in dimensions, the minimum being 0.55 mm. long without mandibles, 
front 0.31 mm. by 0.29 mm., epistoma 0.23 mm., pleurostoma 0.12 
mm.; the maximum 0.70 mm. long without mandibles, front 0.36 
mm. by 0.34 mm., epistoma 0.28 mm., pleurostoma 0.15 mm. 
The larva differs from the larva of Sitona sp., also found on clover 
roots, in being relatively smaller and stouter, without long hairs, and 
eee with more evident distinction between the tho- 
7 IRN racic and abdominal regions. Sitona larve are 
\ always external feeders, H. obscurus larve al- 
ways internal feeders. 
PUPA 
The pupa (figs. 5 and 6) is truncate fusiform 
Hay ihe in shape, with the apex of the abdomensquarely 
EN eee truncated on a line between the caudal spines 
Fic. 4.—Head of larva of the clo. ON the ninth abdominal segment. The wing 
ver root borer; Front view, pads extend to near the hind margin of the 
sixth, and the elytral pads to near the hind 
margin of the fifth abdominal segment. The color of the fresh 
pupa is pearly white to white and shining. Sete on all parts of 
pupa are short, fine, inconspicuous. Setal spines are also short and 
inconspicuous, except the two anterior dorsal spines on the prothorax, 
which are considerably more prominent than other thoracic spines 
and set, and the two very prominent conical, slen- 
derly pointed, and slightly recurved caudal spines on 
the ninth abdominal segment. The two frontal setal 
spines opposite the upper inside margin of the eye 
mark the vertical limits of carine which form the out- 
side margins of crescent-shaped concaveareas. There 
is also a median inverted V-shaped concavity just 
above the pseudolabrum on fresh pupxe. The sculp- 
ture of the head varies with the age of the pupa. 
Anterior and middle femora with two sete of unequal 
size on small papille. Elytral pads rugose. 
The pupa becomes pigmented as it matures; the 
eyes and mandibles become red-brown; wing pads 
dusky; the area around the mouth parts shows faint 
chitinization; later the face, legs, prothorax, and ely- Fic. 5—Pupaof clover 
tral pads assume a faint brownish tinge. The size Ot ee an cee 
varies considerably, typically 2.5 mm. to 2.7 mm. 
long by 1.1 mm. wide. The pupa is found in a pupal chamber at 
the end of the larval mine inside of the clover root. 
ADULT 
The body of the adult (fig. 7) is oblong oval; pronotum slightly 
wider than long, a little narrower than elytra, sides rounded, unarmed, 
strongly arcuate, narrowed roundly anteriorly, without anterior con- 
striction dorsally; head visible from above; elytra deeply striate but 
unarmed except for shagreening posteriorly and laterally, roundly con- 
