INHERITANCE IN THE "WALKING-STICK," 

 APLOPUS MAYERI. 



CHARLES R. STOCKARD. 



The family Phasmatidae, as is well known, shows some of the 

 most striking cases of " protective resemblance" found among 

 the insects. Several of the genera are typically stick-like to a 

 surprising degree while members of the genus Phyllium resemble 

 in detail a leaf-like structure. These animals are no doubt pro- 

 tected by their imitative forms provided they behave in a cer- 

 tain manner. In fact the protection or concealment of such an 

 animal depends as largely on its behavior as upon its resem- 

 blance to surrounding objects. In order to ascertain whether 

 these so-called protectively adapted insects really exhibited a 

 "protective behavior" I 1 studied the habits of the "walking- 

 stick," Aplopus mayeri, which is abundant on the Tortugas Islands, 

 Florida. These large insects were found to behave in a manner 

 almost ideal for their concealment among the twigs and stems 

 of the plant on which they feed, Snriana inaritiina. 



My study was made during a season, June and July, when the 

 enemies of Aplopus were extremely rare on these islands. In the 

 spring and fall, however, the great numbers of migrating birds 

 which stop here no doubt devour many of these large Orthoptera 

 in spite of their almost perfect concealment. But for their pro- 

 tective resemblance and habits birds might easily exterminate 

 such slow-moving flightless insects within a few seasons, in fact 

 the existence of creatures like Aplopi on these small islands is 

 really dependent upon their ability to be passed unobserved by 

 birds migrating between the eastern United States, West Indies 

 and South America. 



The question arises whether the protective behavior in Aplopus 

 is fully developed on hatching from the egg or whether it is at- 

 tained with their large size and mature condition. In order to 



1 " Habits, Reactions and Mating Instincts of the ' Walking-Stick,' Aplopus may- 

 eri," Science, N. S., XXVII., 1908 Publication No. 103, Carnegie Institution, 

 Washington, 1908. 



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