Tmccts. 7;t31 



contains an iinniiMiso liost of individnuls. l*'roni galls of this desciip' 

 tion I obluinud about twolvc liinuliod flics, all of wliicli I liavo curo- 

 fiilly examined, and am satisJiod that all arc of tlio fumalu sox. 



On several occasions i have bred numbers of Cynips aplera, but, an 

 in the ])recedinf; cases, all proved to bo females. 



1 do not know whether any one has distinguislied the sexes of 

 Acai'i ; 1 have failed to do so ; and it has appeared (o uui, in om^ 

 instance at least, that there is appartmtly no (bstinction of mux : 1 am 

 led to imagine, judging from what 1 liavo observed, that tlie species 

 might be perpetuated for ever without, so far as I can see, any inter- 

 vention of a mah) sex. In \XM 1 obtained a large su|)ply of the 

 larva of Anthophoru Acurvorum ; these I placed upon a bed of wool in 

 a (hit box ; tlie majority of the larvic wero in the earthen cells formed 

 by the l)eo. In Iho autnnni a few changed to pupai, tiien to jjorfect 

 insects ; the rest passed the winter in th(< larva state. On the return of 

 spring I examined tiie (!(>nlents of tlie l)ox ; ail were in tlu> lurva state; 

 but to my mortification numbers were attackctl by a species of Acarus : 

 this 8])i)cies is described by Newport in tln^ ' liinn(Min Transactions,' 

 where an account of its habits is given at length. 'I'lie Acarus is of 

 snudl si/(>, and has a globular, Kemi-transparent abdomen, rather 

 smaller than a nuistard-seed ; tiie thorax is short, and has attached 

 to it a number of ai)pareutly useless higs, for tiie head of tlio creaturo 

 is buried in the body of the bee-larvu, which, as far as has been 

 observed, it never (piils, but remains in a stationary position during 

 life, fiuHling upon tin; body of the bee-larva; when it arrives at ii 

 state of nuiturity it dies, still attached to the larva. Notliing now is 

 left of its victim but a drie<l, shriv<;lled skin ; all nuition ceases on tho 

 part of tho Acarus, when the swollen abdomen bursts, scattering 

 atoms of dust on (;vory thing around it, these atoms being in fiicl thu 

 eggs of tho Acarus. Not less than forty Acari atla(;k a single boo- 

 larva. A small portion of this dust, spriiddetl upon a larva, invariably 

 produces tho Acarus in a few days' time. Some of this powder 

 which still renuiined in a few of tho earthen cells which I had by nio 

 last year, it being six years since I obtaintid it, produccxl tho A<rarus 

 when si)rinkled on the larva of AnthoplKua. Now, idthough I have 

 examined these Acari rtipoatedly under IIh! microscope when (e«!diug, 

 1 have never observed the slightest difference amongst them in form 

 or otherwise ; all were, apparently, ])ermaucntly attached to tho bee- 

 larva from tho time of their birth to tho time of their death. By what 

 process the eggs are fertilized 1 am at a loss to conjecture. Appa- 

 rently the only mode whereby eggs beconm fertiliziid in the body of 



