26 MASS. EXPERIMENT STATION BULLETIN 189. 



Thoracic feet and crotchets on abdominal and anal feet dark brown. 

 Preanal plate pale amber. 



Third Instor (see Plate I, Fig. 4). — Average measurements of 16 indi- 

 viduals, just molted: Length, 4.75 millimeters; head width, .68 milli- 

 meter. Body subcylindrical and darker than preceding instar. Ab- 

 dominal segments, except 9 and 10, crossed transversely by shallow grooves. 

 Anterior stigmatal and subventral tubercles of prothorax contiguous, 

 nearly concolorous with head and somewhat corneous. Remaining body 

 tubercles as before. 



Head deflexed, dark brown in color. Clypeus nearly concolorous with 

 head, and not so distinct from frontal piece. Labrum pale brown. 



Prothoracic shield averages .71 millimeter wide. Line of division 

 down middorsal line semi-distinct for one-half distance from anterior 

 border. Venter of prothoracic segment dark. 



Thoracic legs, abdominal legs and preanal plate as before. 



Fourth Instar (see Plate I, Fig. 6). — Average measurements of 12 

 individuals, two or three days after molting: Length, 12.5 milhmeters; 

 head width, 1.03 millimeters. Body cylindrical, varies in color from 

 opaque white to pale or dark amber. Some individuals show, indistinct 

 median and subdorsal longitudinal reddish brown or gray lines on the 

 dorsum. Tubercles of medium size, arranged similar to second instar. 

 Prothoracic tubercles not contiguous, slightly darker than remaining 

 body tubercles. Spiracles nearly concolorous with tubercles. 



Head slightly paler than preceding instar. CljT^eus not distinctly 

 marked off from front, concolorous with head, trapezoidal; average height, 

 .12 millimeter, average width, .47 millimeter. Labrum dark brown. 

 Mandibles dark brown, not protruding. Distal segments of antennse 

 dark amber, otherwise nearly colorless. 



Prothoracic shield averages .98 millimeter wide, distinctly di\'ided 

 along middorsal line, slightly paler in color than before, and often assuming 

 a yellowish tinge on anterior border. Venter of prothoracic segment 

 slightly darker than venters of remaining segments. 



Fifth Instar (see Plate II, Fig. 8). — Average measurements of 13 

 individuals, three daj'S after molting: Length, 14.46 millimeters; head 

 width, 1.66 millimeters. Body cylindrical, varies in color from dusky 

 opaque white to light pink, with distinct median and subdorsal longi- 

 tudinal reddish brown, gray or pink lines on the dorsum. Tubercles 

 medium and distinct, pale at center and surrounded by a dusky black 

 ring which in turn is surrounded, on the abdominal segments, by a 

 wider, pale amber-colored band. Tubercles on thorax uniformly dark 

 amber, same arrangement as before. Spiracles nearly concolorous with 

 tubercles. 



Head polished dark brown, not quite as high as wide. Clj'peus dis- 

 tinctly marked off from front, central area paler than head; average 

 height, .18 millimeter, average width, .66 millimeter. Adfrontal pieces 

 distinct for first time and extend to the vertex. Labrum dark brown 



