354 A. H. STURTEVANT 



as my observation goes this occurs only after a prolonged court- 

 ship in which the female has seemed unwilling to mate, and is, 

 I think, due to the male not getting a good -hold. I do not 

 know whether or not such pairings are successful. Ordinarily 

 copulation lasts about 20 minutes. 4 



EXPERIMENTS ON OTHER INSECTS 



There is a considerable body of evidence relating to the ques- 

 tion of sex recognition in the Arthropods. A short review of 

 the subject and a bibliography are given by Chidester ('11), 

 so I shall confine myself here to the evidence dealing with 

 insects. There is evidence from several groups of insects, but 

 most of it points the same way. Sex recognition at a distance 

 is by smell, but the actual process of copulation depends upon 

 the sense of touch. 



In the Orthoptera, Stockard ('08) has observed the male 

 walking stick to pair with the detached abdomen of a female 

 which was fastened to a stick with wires for legs. 



In Coleoptera, Fere ('98) finds that male cockchafers do not 

 pair if the antennae are removed. Males will sometimes pair 

 with males, prov ded the latter have just paired with females, 

 or have been artificially impregnated with female juices. 



Mast ('12) shows that in the firefly the males find the females 

 by means of the flashing lights, signals being made by both 

 sexes. Tower ('06) reports that in Leptinotarsa males normally 

 never try to actually copulate with males, but that if the anten- 

 nae are removed or painted with shellac they will try to pair 

 with any individual they happen to touch. If this individual 

 is a female pairing will occur. If the abdomens of females are 

 removed the males are attracted by them, though not by the 

 wings, head and thorax. Females with their abdomens coated 

 with shellac are not attractive to the males. 



Fere ('98a) found that in the silkworm moth males will pair 

 with other males, which have not been given a chance to get 

 the female odor, if the latter males are sluggish, as after removal 

 of the antennae. Males without antennae will copulate. Kel- 

 logg ('07) has since reported that males without antennae find 

 the females only by chance, while normal ma 1 es go straight to 



4 In 20 cases the duration of copulation was timed with the following result 

 (minutes): }, 5, 16, 17, 18, 18, 19, 20, 21. 21, 21. 21, 22, 22, 23, 24, 25, 26. 27 

 33, 



