Mr, CuRTis*s Ohfervations on Aphides, ycy 



uhich infefls plants very generally-, while the hn^c fpay'es, on a^ 

 geranium that I kept within doors, produced young. In mild 

 winters I have oblervcd, in the month ot January, the fame f[)ecics 

 of Apb/'s in great numbers on various i'pecies of primula without 

 doors, and all the females viviparous. Theie are faels which prove 

 that all j^pbides are not oviparous and viviparous at the fame feafon, 

 but that fome may be wholly viviparous; that all fuch as aie 

 both oviparous and viviparous do not lay e^gs toward the middle of 

 autumn, nor at all during the winter, unlefs a certain degree of cold 

 takes place. 



Moil people will think it a matter of very little moment to man- 

 kind whether an J^phis comes into tlic world with its head or its^ 

 heels foremoft : — it may be fo; yet, as nature's hiftorian, it is per- 

 haps incumbent on us to notice this circum fiance. The young Jphis 

 then is ullicred into the world with its iect foremoft, fee Tab. V,. 

 fig. I., and this act of parturition, unimportant as it may appear,, 

 ferves to difplay the wifdom of the all-provident Author of Nature.. 

 The female Jphis is uRially delivered of its offspring as it fits clofc 

 to the bark of the tree, but not fuddenly and all at once. Two- 

 thirds of the body of the young one is quickly protruded. When it 

 gets fo far, the power of expulfion ceafes, and the delivejy proceeds 

 flowly. Time is thus given to the young one to learn the ufe of its 

 legs, which it foon kicks about brifkly, and the firft fervice it em- 

 ploys them in is to clean away a white fubflance, the remains, 

 perhaps, of the membrane in which it was enveloped in the womb. 



* Thefe eggs were laid in fmall, irregular groups, on the upper as well as on the 

 under fide of the leaves •, they were of a perfe<aiy black colour, and very vifible to the 

 naked eye. I found afterwards that the eggs when recently excluded vi'ere green, from 

 which colour they gradually changed to that which rendered them fo confpicuous. They 

 weie nightly attached to the leaf. 

 i- But 



