20 BULLETIN 173, U. S. DEPARTMENT OF AGRICULTURE. 



SECOXD STAGE (FCLL-GROWX LARVA). 



Total length 1.833 mm.; length of head 0.15 nun., width 0.1083 mm.; length of 

 prothorax 0.1833 mm., width 0.2166 mm.; length of mesothorax 0.1833 mm., width 

 0.466 mm. Length of antennae 0.2833 mm.; segment I 26/i, II 50/c, III 76,», IV 66/i, 

 V 14/£, VI 16«, YII 33,«. Antennae: Segment I short cylindrical; II obtuse spindle- 

 shaped; III spindle-shaped, about as long as I and II together; IV nearly as long as 

 III, broader than the rest, subcorneal; V short, narrow cylindrical; VI slightly nar- 

 rower and longer than V; VII twice as long as VI, narrower and cylindrical. All 

 joints transversely striated and with a few inconspicuous white hairs. General color 

 faintly yellowish white, obtusely fusiform in shape. Body longitudinally and laterally 

 faintly striated. Head quadrate; eyes prominent, dark reddish brown, situated a 

 little in advance of the middle; mouth cone broadly rounded, nearly as long as 

 the head, extending to the middle of the prosternum. Prothorax large, slightly 

 wider than long, diverging posteriorly. Mesothorax and metathorax short and broad, 

 twice as wide as long, subequal, in length about as long as prothorax. Abdomen 

 broad, gently rounded, 10-segmented, broadest at segments V and VI; first eight 

 segments subequal; segment IX distinctly longer, tapering to apex, the posterior, 

 edge armed with a circle of strong, short, thick wedge-shaped spines, the two medio- 

 dorsal and medioventral ones shorter and smaller; segment X slightly tapering, not 

 quite as long as segment IX. Lateral edges of abdomen finely serrated, also with 

 a few long inconspicuous white hairs which are more prominent on segment X. Legs 

 strong; femora and tibiae about equal; tarsi one-jointed, ending in a single black claw. 

 (PL I, fig. 4.) 



NUMBER OF MOLTS; DEVELOPMENT. 



When first hatched the larvae are active and start feeding imme- 

 diately and soon become more robust. At the end of about seven to 

 eight days they molt into second-stage larvae, where (see description) 

 they are still more robust and show also other differences. The total 

 time required for the development of the larvae is about three weeks, 

 although this period is shorter during warm weather. 



PREPTJTA (FIRST STAGE). 



Total length 1.333 mm.; length of head 0.1 mm., width 0.116 mm.; length of pro- 

 thorax 0.183 mm., width 0.266 mm.; width of mesothorax 0.35 mm.; length of abdomen 

 0.666 mm., width 0.383 mm. Shape similar to adult; color translucent white, deeply 

 tinted with brown. Head subquadrate. about as broad as long, eyes dark reddish 

 brown. Mouth-cone broadly rounded, extending to about one-half length of the pro- 

 sternum. Antennae extending backward on each side of head, apparently four-jointed; 

 first three segments nearly subequal in length, about as broad as long, thick and 

 unwieldy; segment IV about as long as remaining joints, clublike, and tapering to 

 an obtuse point. Antennae with a few inconspicuous white hairs. Prothorax nearly 

 twice as long as the head, broadly rounded posteriorly. Mesothorax broader; wing 

 pads short, those of first pair of wings extending to distal edge of third abdominal 

 segment. Abdomen 10-segmented, widest at III and IV, segments gradually tapering 

 from there posteriorly. First eight segments subequal, IX and X longer, distal end 

 of IX with broad spines somewhat similar to those of second-stage larvae but shorter 

 and smaller. Legs stout, similar to those of full-grown larva, whole body with sparse, 

 light-colored, inconspicuous hairs. (PL I, fig. 5.) 



