15. 



16. 



Lower part of mesepimeron (Fig. 23) with 3 or 

 more fine long bristles; mesonotum frequently 

 patterned with light gray-brown, but occasionally 

 with reddish brown. A northern transcontinental 

 woodland species that is locally abundant in the 

 woods of the northern half of Illinois; rare in 

 light traps. Typical form of stimulans 



Lower part of mesepimeron with none to 2 fine 

 long bristles 16 



Mesonotum with a fairly narrow reddish brown 

 stripe, flanked with white or cream (Fig. 54). A 

 northern transcontinental species that is locally 

 abundant in the vicinity of savanna pools in the 



northern fifth of Illinois. Typical form of 



fitchi 



Mesonotum with reddish brown central area wider 

 than the stripe shown in Fig. 54 or area not well 

 defined. Variant forms (for which reliable iden- 



FlG. 40. — Aei/es arosshecki. portion of wing. ( ihe scales on 

 the veins art wider than those in Fig. 41.) 



Fig. 41. — Aciles s:imu!aiu. portion of wing. 



tification characters have not yet been found) 



of excrurians 



fitchi 

 stimulans 



17. Integument and scaling bright golden yellow, except 



for a few small black-scaled areas. A southern 

 species that is found locally in extreme southern 



Illinois f ulvus pallens 



Integument gray, dark brown, or black, with few or 

 no yellow scales 18 



18. Mesonotum with a definite wide mesal silvery stripe 



flanked by dark areas ( Fig. 45-47) 19 



Mesonotum either without a mesal silvery stripe, or 

 with a narrow one separating 2 dark stripes, these 

 in turn flanked by light areas ( Fig. 55 ; 21 



19. Silvery stripe extending posteriorly only two-thirds 



of the total length of the mesonotum (Fig. 45). 

 A southern woods-edge species; the only Illinois 



record is from Massac County infirmatus 



Silvery stripe extending full length of mesonotum, 

 including scutellum (Fig. 46) 20 



20. Silvery stripe of mesonotum wider than dark flank- 



ing areas (Fig. 46). A shy woodland species 

 common but rarely seen in central and southern 



Illinois dupreei 



Silvery stripe of mesonotum no wider, often nar- 

 rower, than dark flanking areas (Fig. 47). Two 

 southern and eastern woodland species whose 

 eggs and females are indistinguishable; one e^g 

 of tormentor and one female belonging to one of 

 these species have been collected at L'rbana. and 



one female at L'nionville atlanticus 



tormentor 



21. Abdomen with pale scales forming a mesal stripe 



along the entire dorsum (Fig. 48); most of ab- 

 dominal scales pale. A western prairie species: 



the only Illinois record is from Savanna 



spenceri 



Abdomen at most with transverse bands or lateral 

 triangles of pale scales 22 



22. Mesonotum with one or a pair of black or very dark 



mesal areas flanked by gray or silvery areas (Fig. 



49-58) ' .\ '. 23 



Mesonotum fairly uniform in color, brown or taw- 

 ny, sometimes with mesal area reddish brown 

 and lateral areas light golden brown 31 



23. Mesonotum with a mesal pair of dark stripes sepa- 



rated by a mesal stripe of silvery or light golden 



scales (Fig. 5^1, =16) 24 



Mesonotum with an undivided dark mesal area. .26 



24. Dark stripes not extending on to anterior third of 



mesonotum (Fig. 53). A western species known 



locally from central and northern Illinois 



hendersoni 



Dark stripes extending full length of mesonotum. . . 

 2'i 



25. Dark stripes of mesonotum separated by a wide 



mesal stripe of pale scales (Fig. 55). A Holarctic 



10 



