Entomology of the Illinois River. 173 



Pupa [Fig. 6, 7]. — Length 9-11 imn., greatest diameter 

 2.5 mm.; spiracle-bearing segments broadest, slightly 

 swollen dorsally, body with sides gently curving, and 

 tapering gradually towards each end; rather soft-bodied, 

 pale yellowish white, eyes darker; surface smooth, subo- 

 paque, and nearly naked. Head small, with two small de- 

 hiscent spike-like porrect seta? on the vertex. Spiracles 

 of segments 2-4 of the abdomen large and conspicuou.'^, 

 about equal in size, transverse diameter slightly greater 

 than the longitudinal, borne on rounded tubercles. Ven- 

 tral sheath reaching a little beyond end of seventh seg- 

 ment. Apex of abdomen subacute; ninth segment beneath 

 with a faint elevated line at middle, and a small eleva- 

 tion each side. Anterior margin of ninth segment con- 

 spicuously elevated into a broad transverse ridge, bear- 

 ing a row of seven sharp brownish or blackish short 

 longitudinal carinse; ninth segment beneath with a Y- 

 shaped impression [Fig. 7]. 



P. alhalis Rob. 



The larva of this species is doubtless very close to that 

 of ohscuralis, as the difference between the imagos is 

 slight, though constant. One of the moths was captured 

 Sept. 11 at Station C. They have also occurred in our 

 collections from the small lake region of northern Illi- 

 nois and southern Wisconsin ; at Cedar Lake .June 19 ; 

 abundant at Sand and Fourth Lakes Aug. 3 and 9; 

 Aug. 30 and Sept. 3 at Lake Geneva, Wis.; and at Dela- 

 van Lake, Wis., Sept. 5 and 6. Aug. 4 it was taken 

 in Urbana at electric light. 



P. allionealis Wa.]k. {plenilinealis Gr.). 



This is closely related to the European P. stratiotata, 

 whose larva has long been well known, and which differs 

 from that of P. obscuralis in the lesser development of 

 the respiratory filaments, as was shown in treating the 

 latter species. Moths of allionealis occurred at electric 

 lights in Urbana May 29, June 7 and 29. and July 6, 7, 

 23, 27, appearing in numbers on the evening of June 29, 



