4 CIRCULAR 8 4 9. U. S. DEPT. OF AGRICULTURE 



also useful. The head markings of several of the more common species 

 are illustrated in figure 7. The key follows. 



1. Adfrontal sutures terminating in occipital foramen (fig. 1, .4). Skin 



granulose (fig. 2, A—F, L-X). (In some specimens of Peridroma 

 margaritosa (Haw.) sutures nearly reach occipital foramen, but the 



smooth skin places it in the next category) 2 



Adfrontal sutures not reaching occipital foramen (fig. 1, B). Skin gran- 

 ulose or smooth 10 



2. Head more or less fuscous — or ferruginous reticulate (fig. 1, C) or reticula- 



tion absent 4 



Reticulation of head shield entirelv replaced by fuscous freckles (fig. 1, 

 D) 3 



3. Setigerous tubercle II of the abdominal segments about 3 times as large 



as tubercle I (fig. 3). Claws of legs with a distinct tooth at base (fig. 



4, A). March Chorizagrotis auxiliaris (Grote) 



Setigerous tubercle II of abdominal segments about the same size as tuber- 

 cle I. Claws of the legs with base broadly rounded (fig. 4, B). April 



Agrotis vetusta (Wlk.) 



4. Reticulation of head absent, fuscous coloring limited to submedian arcs 



(fig. 1, E). April-May Agrotis orthogonia Morr. 



Head distinctly reticulate. Fuscous coloring not limited to submedian 

 arcs (fig. 1, C) 5 



5. Skin granules very small, flat, or slightly convex, set contiguously, like 



blocks in a pavement, without secondary granules (fig. 2, A, C) 6 



Skin granules coarse, strongly convex, or conical, interspersed irregularly 

 with smaller secondary granules (fig. 2, B, D, E) 8 



6. Tubercle I of abdominal segments nearly, or quite as large as tubercle 



II Agrotis malefida Guen. 



Tubercle I of abdominal segments distinctly smaller than tubercle II 7 



7. Dorsum dark gray. Basal portion of claw distinctly acutely angulate 



(fig. 4, E). March-April Agrotis venerabilis Wlk. 



Dorsum tinged with ferruginous. Basal portion of claw broadly rounded, 

 but slightly angulate (fig. 4, F). Mar ch- April -.Agrotis gladiaria (Morr.) 



8. Skin granules strongly convex, coarse, interspersed irregularly with 



smaller secondary granules (fig. 2, B, D) 9 



Skin granules upright, conical, somewhat retrorse (fig. 2, E). Septem- 

 ber Feltia subterranea (F.) 



H. Tubercle I of abdominal segments nearly or q-uite as large as tubercle II. 

 Fuscous coloration of supraspiracular area strongly intensified subdor- 

 sally on anterior half of each segment. March- April 



Feltia subgothica (Haw.) 

 Tubercle I of abdominal segments distinctly smaller than tubercle II. 

 Fuscous coloration of supraspiracular area not intensified as above 

 May- June Agrotis ypsilon (Rott.) 



10. Skin granulose or spinose 11 



Skin smooth 16 



11. Skin spinose, or, if granulose, granules conical or coarse and isolated, 



closely set but not contiguous (fig. 2, F, G) 12 



Skin granules small, flat, or slightly convex, set contiguously like blocks 

 in a pavement (fig. 2, H, J, K) 13 



12. Skin granules roundingly conical (fig. 2, F). Head coarsely granulose. 



April Lacinipolia renigera (Steph.) 



Skin granules sharp-pointed, spinelike, interspersed with smaller sharp- 

 pointed granules (fig. 2, G). Head smooth, shining. June-Septem- 

 ber Heliothis arm igera (Hbn.) 



13. Each mandible with 4 or 5 distinct teeth. Body not prominently striped _ 14 

 Each mandil 3 with only 2 teeth, anteriorly. Body prominently striped. 



April Xephelodes cm medon ia (Cram.) 



14. Claws of legs acutely angulate at base (fig. 4, M). Dorsal markings not 



rhomboidal Laphygma frugiperda (A. and S.) 



Claws of legs with base broadly rounded (Fig. 4, L, N). A segmental 

 series of rhomboidal infuscated markings on dorsum 15 



