MATING HABITS. 



237 



Table 104. Number of eggs and number of batches of eggs laid by different species 



of the genus Leptinotarsa. 



Concerning the breeding habits of these beetles three facts have been 

 learned which are of importance in succeeding studies. First, the habits of 

 these beetles in normal reproduction are promiscuous; hencetheoffspringfrom 

 any one female may have several different male parents, and from material 

 taken in nature in copulation or otherwise we can not be sure of results in 

 breeding experiments until we have reared such material in experiment for at 

 least one or two generations, and are certain of the purity of the race under 

 experimentation ; second, the eggs are laid and developed in batches, which in 

 the genital passages of the female do not mingle with successive batches 

 that is, each is distinct from that which precedes and from that which fol- 

 lows a fact that has been made great use of in the experiments in the pro- 

 duction of modifications ; third, the conditions of existence may prevent the 

 deposition of the eggs either through the inhibition of copulation or of the 

 development of the ova, or through the mechanical prevention of egg-laying 

 by the inability of the female to secrete in the accessory glands the fluid which 

 enables the eggs to pass easily through the lower part of the genital passages, 

 and which serves also to cement the eggs to the leaves. These three facts are 

 of paramount importance in the carrying on of continued and successful 

 experiments in pedigree breeding and in the experimental production of new 

 races and modifications. 



It has been clearly shown that there is not the slightest trace in the breeding 

 of these beetles of any selective influence due to color or form, that elaborate 

 mating habits are wanting, and that the sole means of sexual recognition is 

 through the olfactory sense and the odoriferous secretions of the accessory 



