88 THOMAS SAY FOUNDATION 



Perla modesta Banks. 



(Plate 12, fig. 1; plate 17, fig. 16-19.) 

 1908. 1'irJn modesta Banks, Trans. Anier. Ent. Soc, 34:255. 



Length to wing tip, male, 10 mm. ; female, 15 mm. Ex- 

 panse, male, 15 mm. ; female, 28-30 mm. 



Color brownish, varied with amber yellow. Head brown- 

 ish at the sides and across the front ocellus (where the 

 color is deepest), with a big trapezoidal yellow spot before 

 the occiput that widens forward and sends 3 lobes be- 

 tween and beside the rear ocelli. There is another pale 

 spot before the middle ocellus and the mouth is pale. An- 

 tennae pale brown, the basal segment darker. Palpi yel- 

 low. 



Prothorax quadrangular about as long as wide, with 

 sides parallel and front and rear ends convex, the last 

 with a small median concavity in the middle. Embossed 

 markings on the sides of the disc faint and not numerous. 

 Middle stripe of yellow parallel sided, and extended to 

 rearward by a triangular spot of yellow upon the front 

 of the brown mesothorax. Wings subhyaline with pale 

 brown veins and with the apical costal space from the 

 tip of the subcosta outward infuscated. Legs yellowish 

 brown. 



Abdomen yellowish brown, darkened at the sides and 

 on the enlarged genital segments. Tails yellowish brown. 



Male. The five short basal segments are ringed with 

 brown across their apical margins. Segments 6 to 9 are 

 longer and thickened. The sterna of 7, 8 and 9 all show 

 subgenital modification, 7 having a ventral oval lobe with 

 notches at its sides, 8 being darkened and thickened 

 across its apical half and 9 being produced rearward into 

 the usual oval upturning subgenital scoop that extends by 

 a third the length of the segment. 10 is divided dorsally 

 to accommodate the retractile U-shaped supra-anal proc- 

 ess whose attachment is marked by a blackish spot on the 

 middorsal line at the base of the segment: the apical 

 angles of 10 are produced into elongate, triangular, 

 prickle-beset lobes that incline upward and rearward. 



Female. The subgenital plate is semicircular, its 

 base covers most of the sternum of 8 and its apex extends 

 well out upon segment 9. There are two darker spots be- 

 side its base, and two others in corresponding position 

 on segment 9. 



Distribution. — Boulder, Colo.; Tolland, Colo. (G. S. 

 Dodds) ; Lawn Lake, Estes Park, Colo., Aug. 27, 1919 (P. 

 W. Claassen) ; Florissant, Colo., June 1907; Beulah, N. 



