THE DESERT HORNED LIZARD 277 



shelter for the nights and cool days. They are 

 active only during the heat of the day, generally 

 confining their activities to the midday hours, 

 but even with them there is a limit to the 

 amount of heat they can stand. During the 

 hottest part of the summer season they seek 

 the shade or go under the sand during the hours 

 of highest temperature and do their feeding 

 during the late afternoon. The least cool 

 weather sends them underground. Their hiber- 

 nating season begins early in November and 

 continues until about the first of March. 



Dr. Bryant, who has made a special study of 

 these reptiles, has accumulated abundant evi- 

 dence to show that these scaly animals are 

 exemplary destroyers of insects. Left to their 

 own devices they destroy an amazing number 

 of ants, noxious beetles, and flies. "Unless 

 very hungry," writes Dr. Bryant, "live insects 

 alone satisfy a Phrynosoma. In fact, their eyes 

 seem unable to distinguish an insect unless it 

 moves, so that this may largely govern the 

 feeding habit. On seeing its prey, a Phrynosoma 

 has a habit of raising and lowering itself on its 

 front legs much as a lizard does when sunning 



