392 Mr Buxton, Animal Oecology in Deserts 



grown as crops and irrigated all through the summer, and the 

 Zizyphus, the food-plant of the two Taruci, is evergreen. Possibly 

 development is retarded or inhibited when the relative humidity 

 falls below a certain figure. The lycaenid Chilades galba is in quite 

 a different biological group : at Amara it is on the wing from June 

 to August abundantly, and rarely during early September; I have 

 examined 80 specimens, the earliest taken 8 June. It appeared 

 that a large number of pyralid moths were only on the wing in 

 the heat of summer in Mesopotamia. 



Belenois mesentina is a vigorous species able to maintain itself 

 in deserts, but found in other terrains also. Grosvenor informs me 

 that it breeds in great numbers continuously through the summer 

 at Tank and Bojikhel, Waziristan; it is the only butterfly on the 

 wing at that time of year. The food-plant (Capparis) is green and 

 succulent all the summer. Possibly the butterfly's abihty to con- 

 tinue breeding through a period of great heat is one of the factors 

 which make it an abundant species over a very wide extent of 

 country. 



