246 



PARTHENOGENESIS. 



'In Part VI of this Bulletin I have remarked on the general 

 occurrence of parthenogenesis in the Mymarid parasites of the 

 genera Anagrus and Paranagrus, which 'attack leaf-hoppers' 

 eggs. The. same phenomenon is still more apparent in the egg- 

 parasite of the genus Oofctrastichiis. The complete life cycle of 

 the type of this genus is about 6 weeks, or twice as long as thai 

 of the Mymarids. I bred colonies of it from numerous parents 

 for a period of about 8 months, but without ever obtaining a 

 single male specimen. Specimens bred by us in Australia from 

 egg-ch'a.mbers of leaf-hopper were all females, and many reared 

 from the same, collected by Koebele in Fiji, yielded only this 

 sex. All specimens so far bred from Hawaiian leaf-hoppers, 

 the parasite being now fully established in these islands, rre 

 females. It will be observed that these facts are in some respects 

 directly opposed to those observed by Dr. Adler in the case of 

 Pteromalns, since he remarks that in general the virgin females 

 gave birt'h ordinarily to males only. In the Mymarids and in 

 Ootctrastichus the virgin females gave birth ordinarily to females 

 only, and in the case of the latter the other sex 'has not yet 

 been seen by us, in observations extending over a year and a 

 half. I may further remark that in the parasites of Dryinidae, 

 Chciloncurns, Echfhrogonatopus and others, the number o^ 

 males falls far short of the females, when extensive rearings are 

 made. 



CLASSIFICATION. 



The greater number of species described in this paper belong 

 to the family Encyrtidae, and to the very extensive subfamily 

 Encyrtinae. Australia is remarkably rich in Encyrtids, thoug'h 

 comparatively few species have been described thence. In the 

 classification of his tribe Encyrtina," Thomson, whose keen ap- 

 preciation of minute structural characters is familiar to all who 

 have used his works, employed the structure of the mandibles 

 for the further division of this tribe. As'hmead in his recent 

 classification of the Encyrtinae follows Thomson, separating the 

 genera into tribes, based mainly on these same mandibular dif- 

 ferences. So far as the AustraHan species are concerned I have 

 not been so fortunate as to be able to appreciate these struct- 

 ures at the value assigned to them by the Swedish and Ameri- 

 can hymenopterists, and I have had considerable doubt as to 

 whether the minute distinctions given are really applicable to 



