28 PARTHENOGENESIS. 



larvse ; a virgin Phyllotoma vagans to deposit between 

 sixty and seventy eggs, but failed to rear anything 

 from them ; one of Eriocampa ovata about thirty ova ; 

 and also got Hemicliroa rufa to lay, rearing males only 

 from the former, and males and females from the 

 latter.* 



Mr. Fletcher also bred two females from virgin ova 

 laid by two Croesus vanish Mr. Bridgman has also 

 got eggs from a virgin ? of E. ovata.% 



I have myself obtained larvae from virgin Strongylo- 

 gaster cingulatus, Phyllotoma nemorata, Hemicliroa 

 rufa, Poecilosoma pulveratum, and reared females from 

 the two last species. 



From these observations it is perfectly clear that 

 complete parthenogenesis occurs in such species as 

 Eriocampa ovata, Poecilosoma pulveratum, and Croesus 

 varus, while the mixed parthenogenesis of Nematus 

 ribesii and N. miliaris is beyond dispute. From the 

 readiness with which so many species deposit ova with- 

 out having had any connection with the males, and from 

 the general scarcity of the latter, it seems evident that 

 further investigation will show that the phenomenon is 

 of very common occurrence. 



Von Siebold in his book has analysed Hartig's 

 Blattivespen with reference to this question, and shows 

 that the German author was unacquainted with the 

 males of 76 species out of a total of 381. A similar 

 analysis of the British species shows that the males of 

 53 species are yet unknown. No doubt many of these 

 are rare and little known forms, so that no great 

 reliance can be placed on them alone as showing the 

 scarcity or absence of males, yet the same result is 

 brought out in another way. Tabulating the species 

 in my collection I find, that in addition to the maleless 

 species noted above, 54 species are represented by 

 females only, so that I have never seen the males of 

 something like a third of the British species. 



As to the precise significance which the phenomenon 



* E. M. M., xviii, 126. t E. M. M.,xvii, 180. J Ent., 1878, 191. 



