AT REST AND ASLEEP 109 



in companies, or at rest for a longer time, or, as 

 it were, for observation, the wings are usually 

 closed tightly back to back ; among the Pam- 

 philini, however, there is a very prevalent custom 

 which oddly combines these two, the hind wings 

 being held horizontal, the fore wings perpendicu- 

 lar or a little oblique ; this gives them a curiously 

 disjointed look, the purpose of which is not easy 

 to see ; perhaps a comparative study of the atti- 

 tudes in males and females, or in those species in 

 which the males have and those where they have 

 not a discal stigma, may lead to some result. 



The need of feeding with erect wings is plain 

 enouo'h m certain instances, as where crowds 

 mingle along the edge of a muddy rut in the 

 road ; and that the same posture is almost invari- 

 ably assumed at complete rest, as for the night, ^ 

 is also easily explained, since that presents the 

 least exposed surface, and one which far more 

 than the upper side of the wings, sometimes very 

 completely, resembles in tint and often in texture 

 or markings the background chosen for rest. 



No creatures seem to be more sensitive than 



1 Some Hesperini, which rest by day with outspread wings, 

 sleep with roofed wings like moths, and very likely all of 

 them do ; we know little of their sleeping attitudes. 



