AUDITORY SENSE OF HONEY-BEE 175 



SO-CALLED VOCAL ORGANS OF INSECTS 



In the higher animals the vocal organs are located in the throaty 

 but in insects we should not expect to find their vocal organs 

 in the buccal cavity, because this class of animals has a totally 

 different organization. Hence, we must look elsewhere for the 

 vocal organs of insects. 



1 . Sound-producing organ of honey-bee 



In 1911, while determining that bees have an olfactory sense, 

 the writer also ascertained that they have a means of making a 

 piping or squealing noise. 



a. Experiments to determine how bees make sounds. Hundreds 

 of worker bees with wings pulled off or cut off were tested, and 

 from mere observations it appeared that the squealing noise was 

 made by the thorax. To be sure that the noise was made by the 

 thorax, the abdomens of several bees were cut off. These mu- 

 tilated bees could walk fairly well and when irritated made the 

 squealing noise. Several other bees with both heads and ab- 

 domens cut off were likewise tested; these were so badly mutilated 

 that in only one case did a thorax make the noise. Bees with 

 wings cut off, when observed under a binocular, further confirmed 

 the view that the squealing noise is made solely by the thorax, 

 because the bases of the wings were seen to vibrate rapidly. 



In 1920 the preceding line of experimentation was continued, 

 and the following results were obtained. The loud buzzing of 

 bees is made by the distal portions of both pairs of wings, while 

 the squealing noise is made only by the bases of the front wings. 

 When worker bees or drones were squeezed, or when their wings 

 were held firmly, or were cut off or pulled off, these insects usually 

 made the squealing noise. When no noise was heard, the insect 

 being tested was placed on a large inverted pan lymg on a table. 

 The pan thus serving as a resonator usually intensified the feeble 

 noise so that the human ear could hear it. Bees with the wing 

 stubs glued did not make the noise, but after dissolving off the 

 glue the insects made the noise as usual. When the muscles 

 attached to the roots or axillaries of the wings were cut, the 



