24 Trans. Acad. Sci. of St. Louis. 



appendages, but never yet lias a male been found with 

 green wings. In some ot the males the wings are hyaline, 

 but observation has shown that this condition usually 

 exists for a short time after moulting and before the 

 pigment is distributed, in many the two pairs of hind 

 legs seem to acquire the darker color before the front 

 ones do; many are seen with the hind legs dark gray 

 while the front pair are still green. These are always in 

 contact with the material upon which the insect rests, 

 the dull, dark bark of trees, etc., while the front ones 

 are held high in the air. 



Near to the center of the wing is a highly pigmented 

 and clearly defined spot which is very conspicuous in 

 the green winged insects, but not so much so in the dark 

 ones. The utility of these is not at once apparent, 

 although one is likely to suspect at first thought that 

 they are to give an aggressive appearance when the fe- 

 male raises her wings in the attitude of fight. When the 

 insect is at rest, one wing partly overlaps the other 

 sometimes covering this pigmented spot. 



Little is precisely known concerning the regulation of 

 colors in this insect, but it has hitherto been generally 

 thought that the males were brown and the females green 

 (Howard). Eiley (1869, p. 170) says: ''The green 

 form is almost entirely confined to the female sex and 

 seems to be the most common color of this sex when full 

 grown." According to Scudder (1896) this dimorphic 

 female was for a time specifically divided, the gray one 

 being called dimidiata and the green one Carolina. But 

 in criticism of this he says that since the two forms occur 

 in the United States he cannot see how they could be 

 specifically separated, since there is no similar distinc- 

 tion in the male, which is never entirely green. 



My own observations have fully satisfied me that the 

 adult females appear not only in the green form (PI. I) 

 and in the gray (PI. V)^- but also in every gradation 



« See also Plates VI and VIII. 



