CHANGE OF HABITS IN ANIMALS 409 



have been found in most counties, from the southern borders 

 to the Orkney and the Shetland Islands, and although these 

 immigrants lay eggs which hatch into caterpillars and reach 

 the chrysalis stage, yet for lack of suitable climate the adult 

 moth seldom emerges in Scotland under natural conditions 

 and the mummy shrivels within the pupa case. 



The adult or imago " Death's Head" shows a second 

 interesting change in its habits of feeding. Naturally, it may 

 be seen sipping honey while it hovers in front of some 

 evening flower ; but since man contrived that Bees should 

 collect honey in hives, the " Death's Head " frequently 

 chooses the easier way of creeping within the hives and 

 stealing honey from the cells, a strange habit well known 

 in Southern Europe, a case of which near Edinburgh has 

 recently come to my notice. 



The extraordinary spread of the Colorado Beetle in 

 America was due to a similar simple change of food through 

 cultivation. In its native haunts in Colorado it fed harmlessly 

 on the Sand Bur, a wild species of the potato family, until 

 the cultivated Potato beguiled it, and led it to devastate a 

 continent. 



The Colorado Beetle, however, widened the break with 

 former habits by changing from one type of vegetarian food 

 to new and different kinds a change which can be traced to 

 the competition engendered by the rapid multiplication of 

 the beetles themselves. Before it had spread to the Atlantic 

 coast, many individuals were found to forsake the potato 

 family and to browse upon such plants as cabbages, Smart- 

 weed {Polygonum)) Pigweed {Amaranthus)> and Hedge 

 M LI stard ( Sisymbriu m ) . 



Not only so, but its numbers induced other creatures 

 to change their old established feeding habits, though not 

 always without hesitation and much experiment. For 

 several years Ducks were the only domesticated birds which 

 turned to the Beetle for food, but after a few years Fowls 

 learned to eat, first the eggs, then the larvae, and finally the 

 adult beetles, so that as many as 30 and 40 of these were 

 found in the crops of single chicks, and this not because 

 other food was lacking, but from a newly acquired preference. 



A similar development of habit occurs in our Starlings, 

 which may frequently be seen perched on the backs of Sheep, 



