4 BULLETIN 59, U. S. DEPARTMENT OF AGRICULTURE. 



such, as those of Solanum carolinense, which the larva is more cap- 

 able of manipulating, but there is no tendency to. form a firm, cylin- 

 drical, silk-lined tube, as is the case with the blue or bluish-green 

 larva of Plithorimaea glochinella Zell.. which feeds upon some of the 

 same plants as does Plithorimaea operculella. 



DESCRIPTION OF STAGES. 



THE EGG. 



The egg is pale, translucent, yellowish gray, and strongly irides- 

 cent; it is oval, 0.45 mm. long, 0.35 mm. broad at the middle, mem- 

 branous, and without apparent sculpture. The side upon winch it 

 is deposited is slightly flattened. 



THE LARVA. 



The full-grown larva is 7 to 14 mm. long. The head shield is 

 0.80 to 0.86 mm. broad and fuscous brown. The cervical shield is 

 darker brownish fuscous, with a pale mid-dorsal line, shining, the 

 posterior margin medially straight. The anal shield is brown. The 

 meso thorax and metathorax are deep maroon. The body varies 

 in color through green and gray and is overlaid dorsally with purplish 

 as the larva nears pupation. It is slender, tapering from the meso- 

 thorax posteriorly and set closely and uniformly with minute gran- 

 ules each bearing a minute point, the granules of the thorax and the 

 last abdominal segment being the larger. The tubercles and their 

 setse are inconspicuous, brownish; tubercle II is slightly larger than I. 

 The legs are deep fuscous; the prolegs, green. 



The larva which has just emerged is light grayish, with strongly 

 contrasting dark head and cervical shield. 



Larvae which have been reared habitually upon potatoes are of 

 a larger average size than those reared upon tobacco, and the maxi- 

 mums of the foregoing measurements are from potato-feeding larva?. 

 The larva on potato is more grayish on the body than the tobacco 

 miner and has the mesothorax and metathorax pinkish instead of 

 deep maroon. 



THE PUPA. 



The pupa is yellowish brown, 5.5 to 7 mm. long and 1.5 to 2 mm. 

 broad; it is broadest through the metathorax, tapering both ante- 

 riorly and posteriorly. The head is rather distinct and slightly nod- 

 ding. The abdomen, excepting the last three segments, is set with 

 very minute spinules; it bears at the tip mid-dorsally a short, curved, 

 erect, pointed horn flanked by about four pahs of long hooked 

 spinules, and ventrally a pah of blunt, rounded lobes beneath which 

 are about four pahs of long hooked spinules. Each abdominal seg- 

 ment is set with a transverse row of spinules near the anterior margin. 



