404 SEXUAL SELECTION. [Part II. 



has made, as he iulbrms me, numerous trials, and finds no 

 exception to the rule, that all caterpillars of nocturnal and 

 retiring habits Vv'ith smooth skins, all of a green color, and 

 all Avhicli imitate twigs, arc greedily devom-ed by his birds. 

 The liairy and spinose kinds are invariably rejected, as 

 were four conspicuously-colored species. AVhen the birds 

 rejected a caterpillar, they plainly showed, by shaking 

 their heads and cleansing their beaks, that they were dis- 

 gusted by the taste." Three conspicuous kinds of caterpil- 

 lars and moths were also given by Mr. A. Butler to some 

 lizards and frogs, and were rejected ; though other kinds 

 v>'ere eagerly eaten. Thus the probable truth of xflr. Wal- 

 lace's view is confirmed, namely, that certain caterpillars 

 have been made conspicuous for their own good, so as lo 

 be easily recognized by their enemies, on nearly the same 

 principle that certain poisons are colored by druggists for 

 the good of man. This view will, it is probable, be here- 

 after extended to many animals, which are colored in a 

 conspicuous manner. 



Summary and Concluding Memarlcs on Insects. — 

 Looking back to the several Orders, we haA^e seen that 

 the sexes often difl;er in various characters, the meaning 

 of which is not understood. The sexes, also, often differ 

 in their organs of sense or locomotion, so that the males 

 may quickly discover or reacli the females, and still oftcncr 

 in the males possessing diversified contrivances for retairi- 

 ing the females when found. But we are not here much 

 concerned with sexual differences of these kinds. 



In almost all the Orders, the males of some species, 

 even of weak and delicate kinds, arc known to be highly 

 pugnacious ; and some few are furnished with special weap- 

 ons for fighting with their rivals. But the law of battle 



"^ See Mr. J. Jenner Weirs paper on insects and insectivorous birds, 

 in 'Transact. Ent. Soc' 1860, p. 21 ; also Mr. Butler's paper, ibid. p. 27. 



