﻿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 Paraiiagrus, which 'attack leaf-hoppers' 

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

 parasite of the genus Ootctrastichus. The complete life cycle of 

 the type of this genus is a'bout 6 weeks, or twice as long as that 

 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 bv us in Australia from 

 egg-chia.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. ?re 

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

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

 Ptcroiualiis, since he remarks that in general the virgin females 

 gave birth ordinarily to males only. In the M^-marids and in 

 Ootetrastichns 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 Drvin'd-.e, 

 Chciloncunis, Echthrogonatopiis and others, the number of 

 males falls far short of the females, w'hen 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'li 

 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 Australian 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 



