SEXUAL SELECTION 335 



of Lepidoptera, the mature males generally exceed the fe- 

 males in number, whatever the proportions may be at their 

 first emergence from the egg. 



With reference to the other orders of insects, I have been 

 able to collect very little reliable information. With the 

 stag-beetle {Lucanus cervus) "the males appear to be much 

 more numerous than the females"; but -when, as Cornelius 

 remarked during 1867, an unusual number of these beetles 

 appeared in one part of Germany, the females appeared to 

 exceed the males as six to one. With one of the Elateridse, 

 the males are said to be much more numerous than the 

 females, and "two or three are often found united with one 

 female;** so that here polyandry seems to prevail." With 

 Siagonium (Staphylinidae), in which the males are furnished 

 with horns, "the females are far more numerous than the 

 opposite sex." Mr. Janson stated at the Entomological 

 Society that the females of the bark-feeding Tomicus viUosus 

 are so common as to be a plague, while the males are so rare 

 as to be hardly known. 



It is hardly worth while saying anything about the pro- 

 portion of the sexes in certain species and even groups 

 of insects, for the males are unknown or very rare, and the 

 females are parthenogenetic, that is, fertile without sexual 

 union; examples of this are afPorded by several of the 

 Cynipidae." In all the gall-making Cynipidse known to 

 Mr. Walsh, the females are four or five times as numerous 

 as the males ; and so it is, as he informs me, with the gall- 

 making Cecidomyiise (Diptera). With some common species 

 of Saw-flies (Tenthredinse) Mr. F. Smith has reared hun- 

 dreds of specimens from larvae of all sizes, but has never 

 reared a single male; on the other hand, Curtis says,'° that 



*■ Grunther's "Record of Zoological Literature," 1867, p. 260. On the ex- 

 cess of female Lucanus, ibid. p. 250. On the males of Lucanus in England, 

 Westwood, "Modern Class, of Insects," vol. i. p. 187. On the Siagonium, 

 ibid. p. 172. 



85 Walsh, in "The American Entomologist," vol. i., 1869, p. 103. F. Smith, 

 "Record of Zoological Literature," 1867, p. 328. 



'« "Farm Insects, " pp. 45-46. 



