MATING HABITS. 233 



by selection. However, before natural selection could act, this character 

 must already have been in existence and developed to the extent that it had a 

 selectional value to the species. How such a character could first arise and 

 attain a development sufficient to give it selectional value is quite another 

 problem. Here we simply admit the existence of the character and its use- 

 fulness in the economy of the species when it is developed to such an extent 

 as to be of selectional value; its origin and its development up to this point 

 will be considered later. 



Under normal conditions of existence these beetles, after they have passed 

 the period of feeding and maturing the reproductive products, begin a most 

 ardent courtship, which in a relatively short time results in mating and fertili- 

 zation. In general the males mature first, and begin actively at once to 

 search for females that are in condition for reproductive purposes, or that are 

 willing to receive them in coitus ; for often the female receives the male before 

 her eggs are ready for fertilization. 



The courting habits of these beetles are of the simplest kind. The male 

 normally approaches the female quickly, with his antennae vibrating rapidly 

 in a rotary manner in front of his head, and after a few passes of the antennas 

 over the body of the female he climbs quickly upon her back, and there 

 attempts to secure a firm hold with his legs. If the female is not averse to 

 mating she stands quietly, but if, because of immaturity or for some other 

 reason, she does not care for the attention of this male or of any male at this 

 time, she will run away or take flight at his approach. Even when the male 

 succeeds in gaining a firm foothold upon the back of the female, he can not 

 copulate unless she opens the plates which surround the genital passage. 

 Often when a female is busy feeding a male will approach her quickly and 

 gain a perch upon her back before she is able to escape, and then with ex- 

 truded penis will attempt to force an entrance between the plates which guard 

 the entrance to the vagina, but I have never seen one accomplish this. 

 Usually after a few vigorous attempts to copulate the male retracts the penis 

 and rides around on the back of the female, often for an hour or more, before 

 he becomes weary of this occupation and seeks for a more responsive female. 



When the female is in a receptive condition and the male has secured a 

 firm footing upon her back, he settles backwards upon her body, the two 

 plates which guard the entrance to the vagina are opened, and the penis of 

 the male is allowed to enter. The beginning of copulation is accompanied 

 in both animals by a few convulsive movements which consist of spasmodic 

 expansions and contractions of the abdominal segments in both, and of the 

 raising and lowering of the body of the male. These convulsive movements, 

 however, last for only a short time, when both animals become quiet, and the 

 female frequently resumes her feeding. At intervals of five, ten, or fifteen 

 minutes thereafter, however, the male raises and lowers his body rapidly 



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