206 ENTOMOLOGY 



black. Indeed the various means by which a superficial resemblance is 

 brought about between remotely related insects are often extraordinary. 

 Irrespective of affinity, insects of diverse orders may converge in 

 wholesale numbers toward a central protected form. The most com- 

 plete examples of this have been brought to light by Marshall and 

 Poulton, in their splendid work on the bionomics of South African 

 insects, in which is given, for instance, a colored plate showing how 

 closely six distasteful and dominant beetles of the genus Lycus are 

 imitated by almost forty species of other genera a remarkable ex- 

 ample of convergence involving no less than eighteen families and 

 five orders, namely, Coleoptera, Hymenoptera, Hemiptera, Lepidoptera 

 and Diptera. Excepting a few unprotected, or Batesian, mimics (a fly 

 and two or three beetles), this association is one between species that 

 are already protected, by stings, bad tastes or other peculiarities. 

 In other words, here is Miillerian mimicry on an immense scale; and 

 if Miillerian mimicry is profitable when only two species are concerned, 

 what an enormous benefit it must be to each of forty participants ! 



Strength of the Theory. Evidently the theory of mimicry rests 

 upon the assumption that the mimics, by virtue of their mimicry, are 

 specially protected from insectivorous foes. Formerly, however, there 

 was altogether too little evidence bearing upon the assumption itself, 

 though this was supported by such scattered observations as were 

 available. The oft-repeated assertion that this lack of evidence was 

 due simply to inattention to the subject, has been proved to be true 

 by the decisive results gained in the tropics by several competent 

 investigators who have been able to give the subject the requisite 

 amount of attention. 



From his observations and experiments in India, Frank Finn con- 

 cludes: 



"i. That there is a general appetite for butterflies among insec- 

 tivorous birds, even though they are rarely seen when wild to attack 

 them. 



"2. That many, probably most, species dislike, if not intensely, at 

 any rate in comparison with other butterflies, the warningly-colored 

 Danainae, Acraa viplce, Delias eucharis, and Papilio aristolochice; of 

 these the last being the most distasteful, and the Danainae the least so. 



"3. That the mimics of these are at any rate relatively palatable, 

 and that the mimicry is commonly effectual under natural conditions. 



"4. That each bird has separately to acquire its experience, and well 

 remembers what it has learned. 



