48 February, 



" If these observations are connected with the facts previously made known by 

 Perris (parasitism oi Dryinns pedestris, Dalm., on Athysanus maritimus, Perris) and 

 by J. Mik (parasitism of Gouatoptis pilosns, Thorns., on DeliocepJialus xanthoneurus, 

 Fieb.*), it becomes very probable that the Family Dry'midcR {Proctotrupid ae) are 

 generally parasites of Homoptera {Jassida). On the other part, in comparing 

 the result of our researches with those formerly given by Boheman on the 

 infestation of various CicadellcB by the larvae of Diptera, and in particular of 

 Cicadula vi'rescens, Fall. {Thamnotettix sulpJiurella, Zett.), by the larvae of 

 Pipuncnlus fuscipes, Fall., it becomes equally probable that the Diptera of the 

 Family PipunculidcB arc, in general, parasites of Homoptera of the Family Jassida. 

 " We have been enabled to obtain in abundance, and to study more completely 

 than has been done previously, Dipterous and Hymenopterons parasites of Typlilocyla 

 hitherto deemed extremely rare and captured accidentally. We have also been led to 

 observe some very curious effects of parasitic castration produced by these parasites 

 upon their hosts. 



" The TypMocyhce, with yellow or pale elytra, form a small group of species 

 often living side by side on the same trees, and presenting among them a mimetic 

 resemblance so perfect that it is almost impossible lo distinguish them, even by the 

 most minute examination of the exterior characters. To Mr. James Edwards, of 

 Norwich, is due the merit of having recently drawn attention to the very distinct 

 differential characters derived from the form of the genital armature of the male for 

 the separation of the several species.f 



"In reliance on the studies of this acute investigator, we have recognised that 

 the Typli.locyha of the horse-chestnuts, referred to in our previous notice under the 

 name of T. ro.icp., belongs in reality to two distinct species, T. hippocastani, Edw., 

 and T. Douglasi, Edw., equally common on the trees of the Luxembourg. These 

 two species may be parasitised by Aphelopus and by Ateleiieiira; but Aphelopus 

 infests especially T. hippocastani, and much less often T. Douglasi; on the 

 contrary, Aielenevra is almost ahvays found in T. Douglasi, and very rarely in T. 

 hippocastani.'^ 



Examples are given of the enervating effect of the action of the parasites on 

 the genitalia of both sexes of TyphlocybcB in producing alteration and atrophy of 

 structure and consequent abortion of function, and finally the death of the insects. 

 Another result of the parasitism is thus stated : — 



" Modifications, not less important, are seen in singular organs not hitherto 

 noticed, as far as I am aware, which exist in the males of T. Douglasi and T. hippo- 

 castani, the function of whicli is quite enigmatical. They consist of two invaginations 

 of the integument that divide the ventral surface of the first segment of the abdomen 

 and reach, like fingers of a glove, up to the extremity of the fourth segment, and 

 sometimes a little beyond. Those organs appear to me to be homologous with the 

 phonetic apparatus of the male Cicada. Among the males of T. Douglasi and 

 T. hippocastani infested with Aielenevra and Aphelopus, the ventral invaginations 

 are greatly reduced ; generally they do not reach the second segment of the abdomen, 

 and often exist only as two small gussets on the first segment." 



The author then goes on to notice some variations in the structure and colour of 

 the Aphelopus ; and he adds, that under the name of Atelenevra spuria are possibly 

 confounded different allied species, a question that may be easily solved by rearing 

 the larvae collected with the Typhlocyha. — J. W. Douglas, 8, Beaufort Grardens, 

 Lewisham : Isovemher ZOth, 1889. 



* cf., Ent. Mo. Mag., vol. xix., p. llli.— J. W. D. \ cf., Kut. Mo. Mag., vol. xxv, p. 1.37.— J. W. D. 





