THE SENSES OF INSECTS 109 



loud ' Dzi-dzi ' is heard when both stores and bees are 

 dwindling. The loud ' Dziiiiii ' will be heard when they 

 are too cold. ' Huuuni ' is produced by queenless stocks 

 both in summer and winter. A loud « Wuh-wuh-wuh ' 

 is only heard when breeding is going on, but never when 

 the hive is queenless, or has an unfertilised queen. When 

 water is being collected they produce a loud ' Usiiir,' 

 and young bees playing outside the hive utter a loud 

 ' Shu-u-a,' but as a swarm leaves the hive * Shiusi ' is 

 produced, the normal sound of a swarm being ' Ssssss.' 

 1 Brr-brr-brr ' is heard when drones are being expelled, 

 and the ' Tu-tu-tu ' is known to every bee-keeper as the 

 sound produced by the just-hatched young queen, which is 

 answered by ' Qua-qua-qua ' of those queens still enclosed 

 in their cells. Besides these there are some dozen other 

 sounds produced, differing both in tone and intensity." 



Similarly, the expert naturalist is able to recognise 

 species of grasshoppers and crickets merely by listening 

 to their chirping, and Dr. S. H. Scudder has expressed 

 some of these " songs " in musical notation ; while it is 

 said that in these insects the frequency of stridulation 

 increases with the temperature, and that " the correlation 

 between the two is so close that it is easy to compute 

 the temperature from the number of calls per minute, by 

 means of formulae." Nor is there room for doubt that 

 insects which lack specialised ear-structures are able to 

 hear and interpret the varying sounds produced by their 

 own species. Mayer, a distinguished American naturalist, 

 found that the hairs on the beautifully plumed antenna? 

 of a male gnat " vibrate in unison with the notes of a 

 tuning-fork within the range of sounds emitted by the 

 female. The longer hairs vibrate sympathetically with 

 the graver notes, and the shorter hairs with the higher 

 ones." Another observer (Will) placed a female long-horn 



