XXIV IN SECT A : HYMENOPTERA 381 



she will quickly return with other bees, to whom it appears 

 she must have communicated her find. It seems, however, that 

 more experiments are necessary to establish the degree of 

 power of communication. The humming of bees, which varies 

 in tone and intensity according to the occasion which calls it 

 forth, is produced in two ways : a deeper note, such as heralds 

 the departure of a swarm, is caused by a certain rate of vibra- 

 tion of the wings; whilst a shriller note, such as that of an 

 angry bee, is caused by the vibration of the integument over 

 the thorax, moved by the muscles within which are attached 

 to it. There is a whole gamut of sounds, the exact 

 significance of which we do not know — indeed we are not 

 even sure that these sounds are audible to the bees 

 themselves ; possibly their power of communication by the 

 touch of antennae suffices, without any need for communica- 

 tion at a distance by sound, though on the other hand it 

 is said that the hum of the young bee trying to get free 

 from her cell is noticed by the old queen who is about to 

 leave the hive, and has a curiously agitating effect on her. 



Other Social Bees. 



During the summer Humble Bees are to be 

 ^Bees found living together in small colonies of from 

 200 to 300 individuals, but at the end of the 

 season all die except the young queens who alone can sur- 

 vive the cold of winter, hibernating in some crevice, or under 

 the moss on a bank, or in a small burrow excavated in the 

 earth; consequently, each spring, new colonies have to be 

 started by the solitary young queens. 



The large Earth Humble Bee (Bombus terrestris), 

 Bombus ^j^g commonest species in England, makes her nest 

 underground, often using the deserted burrow of 

 some small animal such as the field-mouse.^ She weaves the 

 little pieces of grass, which the mouse had collected, into a 

 ball with an opening at one side just large enough to allow 

 her to creep through into the central cavity where she will 

 lay her eggs ; then she collects from the earliest spring flowers 

 some pollen and honey, and deposits a little mass of honey- 



1 For most of the following details I am indebted to Mr. Sladen's delight- 

 ful account of Humble Bees in his recently published book (1912). 



