BEHAVIOUR 113 



grazings of New South Wales. In connection with the 

 special aspect of insect behaviour now under discussion it 

 is noteworthy that only since 1895, or thereabout, has this 

 habit ** become a real menace to sheepowners." Here the 

 introduction into the surroundings of certain Australian 

 insects of large flocks of sheep has led to a response by 

 myriads of female flies which has resulted in their larvae 

 feeding on living instead of dead flesh, and has incidentally 

 aff"ected seriously an important activity of mankind. 



These examples of changes in behaviour on a large scale 

 by myriads of individual insects of the same kind serve to 

 emphasise the fact that the habits of these creatures 

 may be remarkably plastic as they are subjected to changes 

 in their environment. While the experimental methods 

 of laboratory study often enable the student to predict with 

 confidence how an insect will react to various kinds 0/ 

 stimulation, the wider survey of insect behaviour as it can 

 be observed by the naturalist in the open country aflfords 

 evidence that the creature's actions are not universally and 

 unalterably stereotyped. The races of the insect world 

 have reached their present conditions of form and activity 

 through the long and changeful history of many generations, 

 and it is fascinating to be afforded clear glimpses of changes 

 in behaviour which assure us that by careful study of the 

 activities of the living insects around us we can learn at 

 least something of the course of that still unfinished story. 



