APHID^E. 



[ 63 ] 



APHRODITA. 



in the pseudova is, however, denied) ; but 

 in the oviparous females, the germ is sur- 

 rounded by a vitellus and vitelline mem- 

 brane in the usual way to form a true egg ; 

 whilst in the viviparous individuals the 

 germinal vesicle itself enlarges and under- 

 goes a considerable change before acquiring 

 an investing membrane, within which the 

 embryo is gradually developed. Balbiani, 

 however, maintains that the viviparous 

 Aphides are really hermaphrodite. 



From the nature of their production, it 

 will be easily understood that the fecundity 

 of the Aphides must be very great. The 

 most prolific species only live for about three 

 weeks, and in that time produce 30-40, or, 

 according to Reaumur, 90-100 young. In 

 these species there may be from 15-17 

 generations in the course of the summer ; 

 and Schrank, starting from Bonnet's obser- 

 vations, calculated the total theoretical pro- 

 geny of a single Aphis in the course of one 

 summer at 23,740,000. Their numbers are, 

 however, constantly kept in check by the 

 attacks of numerous enemies, amongst which 

 we may mention the common Lady-birds, 

 both in their larva and perfect states, the 

 larvae of the Dipterous genus Syrphus, and 

 of the Hemerobiidse, which prey upon them; 

 whilst many of the smaller Ichneurnonidae 

 and Chalcididae attack them for the purpose 

 of depositing eggs in their bodies. 



Notwithstanding these checks upon their 

 production, the plant-lice increase suffi- 

 ciently to render them exceedingly injurious 

 to cultivated plants. The most noxious 

 species are the turnip-flv (Aphis Brassiccs, 

 PI. 36. fig. 3), the bean-fly (A. Papaveris), 

 which also occurs upon the poppy and 

 various other plants, and the hop-fly (A. 

 Humuli). The latter, when it abounds to 

 an unusual extent, causes the almost total 

 destruction of the crop of hops. One of the 

 most abundant species is the rose-fly (A. 

 Roses), which is often exceedingly injurious 

 to roses in gardens, by attacking the young 

 succulent shoots. Lachnus Quercus, a large 

 species with the rostrum three times the 

 length of the body, is found in the fissures 

 of the bark of old oaks ; the other species 

 of Lachmts live for the most part upon the 

 shoots and leaves of coniferous trees ; the 

 commonest is L. pinicola. Eriosoma lani- 

 gera (PL 53. fig. 3) is a common species 

 upon the stems of apple-trees, living in 

 societies in crevices of the bark, on which 

 it forms small, white, woolly patches. Te- 

 traneura Ulmi (PI. 30. fig. 4) lives in small 



gall-like excrescences on the leaves of the 

 elm ; and the Pemphigus bursarius (PI. 36. 

 fig. 5), a woolly species, resides in similar 

 galls on the leaves and foot-stalks of the 

 poplar. Of the subterranean species, which 

 suck the roots of plants, the most abundant 

 is Trama radicis (PI. 36. fig. 6), which 

 occurs upon various composite plants, in- 

 cluding the common dandelion and the 

 garden-lettuce. Forda formicaria (PI. 36. 

 fig. 7) is the species commonly found in 

 ants' nests; it lives in small societies on 

 the roots of grasses, and is tended with 

 great care by the ants. Phylloxera vasta- 

 trix (PI. 53. fiV. 7) is the vine-pest. 



The colouring-matter of the Aphides 

 partakes of the nature of chlorophyll 

 (Sorby). 



BIBL. Westwood, Introd. fyc. ; Walck- 

 enaer, Hist. d. Ins. ; Kaltenbach, Monog. d. 

 Pfanzenlause, 1843 ; Koch, Aphiden, 1857 

 (tigs.) ; Burnett, Sillimarfs Jn. 1854, xvii. 

 pp. 62, 261; Walker, Ann. N. Hist. 2nd 

 ser. i. ii. iii. iv. &c. (1848-49) ; Claparede, 

 Ann. N. Hist. 1867, xix. p. 360 ; Balbiani, 

 ibid. 1866, xviii. pp. 62, 106 ; id. & Signoret, 

 ibid. 1867, xx. pp. 20, 149 ; Boisduval, En- 

 torn. Hort. p. 240 ; Huxley, Linn. Tr. xxii. 

 pp. 193, 221 ; Sorby, Tr. Mic. Soc. xi. p. 352 ; 

 Buckton, Aphides (Monoyr.}, Hay Soc. 

 1876. 



APHRODITA, L. A genus of Annu- 

 lata. One species of this genus (A. acideata) 

 is well known as the sea-mouse, and is 

 commonly found on the sea-coast, and 

 always admired on account of the splendid 

 iridescent colours reflected from its spines 

 and bristly hairs. Body from 3 to 5 inches 

 long, 1^ broad, and oval ; back of an earthy- 

 colour. Head small, entirely concealed!, 

 with two round clear spots, or eyes, on the 

 vertex. The hairs and bristles" run down 

 each side of the body ; the back is roughish, 

 with a thick felt of hair and membrane 

 forming a kind of skin. When this is cut 

 through, fifteen nearly circular plates or 

 scales (elytra) are found on each side, 

 which partly cover each other. If two of 

 the plates lying next each other be sepa- 

 rated, we then see upon the intermediate 

 ring small tubercles divided by a pit, fur- 

 nished behind with pectinate appendages, 

 the gills or branchiae. 



Antennae minute ; palpi large, subulate, 

 jointed at the base. Mouth with a large 

 retractile edentulous proboscis ; the orifice 

 encircled with a short, even, thick-set fringe 

 of compound penicillate filaments divided 



