THE STUDY OF ANIMAL LIFE CHAP. 



by Bates in Tropical America (1862), then by Wallace 

 in Tropical Asia and Malaya (1866), and by Trimen in 

 South Africa (1870) " ; while Kirby, in 1815, referred 

 to the advantage of a certain fly being like a bee, and of 

 a certain spider resembling an ant. 



The constant conditions of mimicry are clearly and 

 tersely summed up by Wallace. They are :- 



1. That the imitative species occur in the same area, 

 and occupy the very same station, as the imitated. 



2. That the imitators are always the more defenceless. 



FIG. 15. HUMMING-BIRD MOTH (Macroglossa Ulan), AND 

 HUMMING-BIRD (Lophornis (jonldii). 



(From Bates.) 



3. That the imitators are always less numerous in 

 individuals. 



4. That the imitators differ from the bulk of their allies. 



5. That the imitation, however minute, is external and 

 visible only, never extending to internal characters or 

 to such as do not affect the external appearance. 



Many inedible butterflies are mimicked by others quite 

 different. Many longicorn beetles exactly mimic wasps, 

 bees, or ants. The tiger-beetles are mimicked by more 

 harmless insects ; the common drone-fly (Eristalis) is like 



