ON BEES' WINGS 111 



the vibration of the wings, but it has been shown 

 that a loud buzzing noise can be emitted by bees 

 which have lost their wings ; this proceeds from 

 the spiracles or holes in the outer covering of the 

 creature through which it breathes. It is there- 

 fore not always easy to say how much of the hum 

 is caused by wing vibration and how much by the 

 action of the spiracles. Some, in fact most, of 

 our solitary bees are almost silent in flight, and 

 their note can be heard only when large numbers 

 are flying together ; others have a very peculiar 

 shrill hum, by which even the species can almost 

 be recognized. In bright, hot, sunny weather 

 their flight is more rapid and their note attains a 

 higher pitch. The bees with the highest pitched 

 hum with which I am acquainted are the two 

 smaller species of Anthophora and Saropoda 

 bimaculata. 



In early spring, when it is hot in the sunshine 

 and cold when a cloud covers the sun, it is no 

 unusual thing to see a bee drop to the ground. 

 The cold seems to paralyze altogether their 

 powers of flight. When at rest a bee folds its 

 wings along the sides of its back, but only in the 

 wasp tribe is there the arrangement for them to be 



