86 UNITED STATES NATIONAL MUSEUM BULLETIN 276 



size of the eighth stemite in figure 37 with figures 38-51 which are all 

 drawn to the same scale, using specimens with a 25-27 mm. wing- 

 spread); the "arms" of the eighth stemite short (fig. 37), so that the 

 total length of the eighth stemite approximately equals the maximum 

 width. Accessory claspers as in figure 12. 



ADULT FEMALES (females in figs. 119-139).— Coloration more 

 constant than males, but varying from yellow to yellow-brown ; wings 

 usually light yellow-brown; forewings crossed with two brown lines 

 (figs. 130, 138, and 139), the outer line often more distinct than inner. 

 Lower surface of wings darker than upper, usually brownish with a 

 single darker line running across both wings. Epiphysis usually longer 

 than second segment of foretarsus and distinctly curved (fig. 76), 

 rarely smaller or absent. 



FEMALE TERMINALIA. — Genital plate entirely sclerotized, vari- 

 able in shape, but wider than long; ostium near the center of genital 

 plate (fig. 83) and flanked by a shallow depression on either side. Ovi- 

 positor lobes as in figures 81 and 82 with no pronounced dorsal lobe. 



ADULT DIAGNOSIS.— The only two North American species likely 

 to be confused with disstria are M. constrictum (figs. 140-160) and M. 

 tigris (figs. 161-175), both of which have dark lines on a lighter ground 

 color and whose distribution overlaps that of disstria in part. In the 

 past these two species often have been confused with disstria. 



Male constrictum usually have the outer line more sharply bent 

 toward the base of the wing near the costal margin (fig. 140) than 

 do male disstria, while male tigris usually have the outer line more 

 sharply bent toward the tip of the wing (fig. 162). The best character, 

 however, to separate male disstria from any other North American 

 species is the shape and size of the epiphysis. It is about % as long as 

 the tibia and distinctly curved (fig. 75) . This character appears to be 

 100 percent reliable since no male disstria has ever been examined 

 which did not have this distinctive epiphysis. All other males of North 

 American species have an epiphysis which is less than ){ the length 

 of the tibia, or if larger than )i the length of the tibia, it is not distinctly 

 curved like that of disstria. The male genitalia are also quite distinctive, 

 with the "arms" of the eighth stemite short (fig. 37), so that the total 

 length of the eighth stemite approximately equals the maximum 

 width. In all other North American species the "arms" are longer, 

 so that the total length of the eighth stemite exceeds the maximum 

 width (figs. 38-51). 



Adult female disstria are not as easily identified by color pattern as 

 males, and they are more likely to be confused with M. californicum and 

 its subspecies than with constrictum or tigris. Female constrictum (females 

 in figs. 140-160) are fairly dark, somewhat dull reddish-brown, and 



