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HARDWICKE'S SCIENCE-GOSSIP. 



rambling over and amongst the stout and shining 

 apterous oviparous females were several lean, lanky 

 individuals, also apterous, which I at once, from 

 prior observations on the aphis of a sallow, detected 

 to be males. There were only one winged aphis, 

 and a few pupa;, observed ; and the majority were 

 immature apterous individuals : during the last week 

 in August winged aphides, as well as pupae and 

 apterous viviparous females, were numerous. 



Cutting off a twig that had upon it many oviparous 

 females and a few males, as well as plenty ova and 

 some larvae, I brought it home and put it under 

 observation. Also, I took a clean young shoot of 

 ivy and put it into a bottle with water, placing 

 thereon a few of the stoutest oviparous females, and 

 isolating them ; also, put one into a small box. On 

 the following day on examining the isolated shoot, 

 I found that half-a-dozen ova had been deposited 

 on the upper surface of its leaves ; and in the box 

 was found one ovum. Later, more ova were de- 

 posited by isolated individuals. Moreover, more than 

 once while I have had the aphides under direct 

 observation, a female has deposited an ovum, the 

 process being slow and giving plenty of time for 

 minute observation : had I not already been aware 

 that these were oviparous females, I should certainly, 

 on a casual glance with the naked eye, have thought 

 that a young aphis was being ushered into existence, 

 and not an ovum ;' in size and general outline the 

 two, during delivery, are not so much unlike each 

 other. That the smaller lean apterous aphides accom- 

 panying these oviparous females are males, there has 

 been evidence clear enough, since most of them paired 

 some time after being brought within doors, the first 

 two on the second day ; hence it seems evident they 

 were in waiting on the full sexual evolution of the 

 females. Of one couple that I isolated in copuld, the 

 female afterwards deposited ova. 



The ova are deposited in greatest numbers on the 

 upper surface of the leaves ; and in less numbers on 

 the under surface and in the axils of the leaves, as 

 well as amongst the adventitious roots, or rootlets, of 

 the young shoots. They are, when first deposited, 

 of a pale yellow colour, smooth, shining, semi-opaque, 

 with contents apparently homogeneous, and are 

 covered with a very sticky substance which securely 

 attaches them to the object upon which they are laid. 

 In form they are oblong, and are i-45th of an inch 

 in length by about one-half that in breadth. They 

 become shining jet-black in four or five days after 

 deposition, having passed through deep yellow and 

 brown. 



Description of the ivy aphis. — Apterous vivi- 

 parous female : length, 2~32nds inch ; stout, and 

 moderately nimble ; colour of the entire body is a 

 red-brown, the dull purple hue being caused by a 

 general coating of bluish-white meal or very fine 

 short down ; limbs, pale colour, nearly white, with 

 black knees and feet ; the antenncc and rostrum are 



of the same ground colour as the limbs, and have 

 their extremities also black ; the cornua and the 

 caudal appendage are black. Pupa : of same length, 

 as nimble, but less globose and lighter in colour than 

 vivip. fern., more especially in the largely developed 

 thoracic region, which is pale greenish-yellow ; wing- 

 cases dusky, nearly black ; the limbs, antennae, 

 rostrum, cornua and caudal appendage coloured as 

 in female ; is also meal or down-covered, giving the 

 purple bloom : all the wingless brood have this 

 purple bloom : very young ones possessing it, though 

 at birth they are without it — are naked, and are then 

 of a reddish or orange-brown colour, the limbs, 

 antenna;, rostrum, and cornua being delicately 

 colourless and purely transparent. Imago (winged 

 form): darker, nearly black ; the head, thorax, antenna;, 

 cornua and caudal appendage are black, the abdomen 

 dark brown, nearly black ; the limbs and rostrum as 

 in vivip. fern, and pupa, only darker ; is without the 

 meal or down ; length, 2~32nds inch. Apterous 

 oviparous female : in size, form and colour. is similar 

 to the vivip. fern. ; excepting that when full of ova 

 and about to lay it is more rotund or swollen, and has 

 the dorsum shining, which is probably clue to disten- 

 sion by the comparatively large ova, and the posterior 

 portion of the abdomen beyond the cornua prolonged 

 taperingly considerably ; after the deposition of an 

 ovum, the posterior projecting rings of the abdomen 

 are retracted. Apterous male : in colour, is like the 

 imago ; in build, is lean and lanky, linear and much 

 shorter than the other four forms, being only 3~64ths 

 inch long, while the limbs and antenna; are longer 

 and stronger ; the antenna; are fully as long as the 

 body. In all, the cornua are well developed, slightly 

 tapering and cylindrical, and a little curving. 



Are the winged individuals of this species of aphis 

 viviparous females, evolved for the dissemination of 

 the species ? From observations on an aphis that 

 here attacks a tall hawkweed (I/ieracium), it 

 appeared very probable that the cycle of aphid 

 existence began on it as early as June 17th in winged 

 viviparous females, which, then alone, were on the 

 following day accompanied by many small apterous 

 larva;. 



Sir J. Lubbock is of opinion that those aphides 

 that are attended on and milked by the ants are not 

 only protected by them, but that they are probably 

 benefited by having their emissions of honey-dew 

 removed by the ants. However this may be, I have 

 observed that when unmolested by the ants the aphis 

 of the ivy forcibly ejects to some distance the drop 

 of liquor immediately on its welling up, as does the 

 aphis of the sycamore ; and it is perhaps reasonable 

 enough to suppose that by their continued caresses 

 the ants provoke prematurely these anal emissions of 

 the coveted liquor, or honey-dew, which they at once 

 secure. 



What is the function of the well-developed cornua 

 in this and many other species of aphis ? Certainly 



