CHAPTER IV. 



HABITS AND INSTINCTS IN LEPTINOTARSA. 



In the preceding chapters on geographical distribution, variation, and color- 

 ation in the genus Leptinotarsa morphological characters alone were consid- 

 ered, and the ways in which they show evidences of evolution. In this chap- 

 ter we shall have to deal with characters and processes that are physiological, 

 instinctive, and selective. These we shall discuss under three general heads : 

 (i) Habits and instincts connected with reproduction; (2) habits and 

 instincts connected with hibernation and aestivation ; (3) habits and instincts 

 connected with self-preservation. 



HABITS AND INSTINCTS CONNECTED WITH REPRODUCTION. 



A considerable portion of the habits and instincts found in the genus Lep- 

 tinotarsa are centered about the reproduction of these beetles, and contribute 

 directly or indirectly to the success or failure of this process. Some of these, 

 such as the mating habits, are concerned directly in the reproduction of the 

 species, while others, such as preferential or selective mating, while they are 

 not so vital to the perpetuation of the species, are of paramount importance 

 in the molding of the character of the subsequent generation. Of signifi- 

 cance also is the adaptation exhibited by these beetles in the habits and 

 instincts which center around the process of reproduction ; and inasmuch as 

 these habits and instincts have at various times shown their sensitiveness to 

 the processes of evolution by being modified permanently in experiment in 

 the same way as have morphological characters, an attempt will now be made 

 to gain as clear an understanding as is possible of these habits and instincts 

 as they occur naturally in the genus, and of their importance to the species 

 displaying them ; for by this means may be gained a basis in fact for the dis- 

 cussion of the modified conditions that have been produced in experiment. 

 Finally, as much as possible must be learned concerning the adaptation of 

 these characters to the needs and surroundings of the individual species. 



MATING HABITS. 



As far as I have been able to discover, the mating habits of these beetles are 

 much the same in all the species in the genus, so that a description of them in 

 two or three species will suffice for all. 



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