168 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



the checkered white for the female of the orange tip. But P. froto- 

 dice keeps always to the open, whereas A. genutia does not leave the 

 woods, and the flight of the former is higher and faster than that of 

 the latter. 



The early-spring form of the cabbage butterfly {P. rapae) is more 

 or less confined to the borders of woods, occurring in quite the same 

 situations as the corresponding form of the checkered white. The 

 nervous, fluttering, direct flight of the checkered white is very dif- 

 ferent from the much more irregular, zigzag, and indolent flight of 

 P, rapae, in wdiich the wing beats are slower and the arc through 

 which the wings are moved is greater. 



The habits of the late-spring form of this butterfly are so very 

 different from those of the early-spring form as to make the two 

 forms seem like different species. Like the late-spring form of the 

 cabbage butterfly {P. rapae), it is a butterfly of the open country, 

 where it is far commoner than it is near the borders of woods. But 

 unlike the corresponding form of the cabbage butterfly it frequents 

 the more barren and more exposed and higher areas of the open 

 fields. 



The flight of the late-spring form of Pieris protodice is very fast, 

 but also very irregular, the butterfly dashing this way and that and 

 often doubling on its course in the most erratic fashion, always 

 keeping about 3 feet above the ground. When frightened it makes 

 off at amazing speed with a rapid succession of wild dashes of 

 about 10 feet from side to side, but it does not rise above the usual 

 level of flight. If very badly frightened, the angles between the 

 straight dashes become so sharp that although the actual speed of 

 travel is increased the speed in a straight line away from the pur- 

 suer is much reduced, and the insect may be easily followed up 

 and intercepted. The males have a somewhat faster and more ir- 

 regular flight than the females, but the difference in the flight of 

 the two sexes is very slight. 



A male and a female fluttering about each other dash this way and 

 that with great rapidity, now rising as much as 20 feet above the 

 ground, now coursing about just above the grass tops. Their actions 

 remind one more of the actions of skippers than of the actions of 

 other pierids. 



The flight of the late-spring form is somewhat less fluttering or 

 tremulous than that of the early-spring form, and, although it is 

 stronger and faster, it resembles the flight of P. rapae much more 

 closely than it does that of AntJiocharis genutia. 



The summer form resembles the late-spring form in habits, but 

 it is rather less active and less shy. 



The early and late spring forms, like all our spring pierids, pay 

 little attention to flowers, spending practically all their time on 



