iMJUKIOUa TO TBE^/TUKirir CROP. 3S1 



iia niuutli cotiHiiiU) of a Uiin tube, Kotn«tiai6ft threeofourthn of iIk Icngllt of 

 its bo<ly, and when unciiiploye<l it in foUl«d along the breast to uear tlic bnMe 

 of the second pair of legs. With this instrument it p^inps up th« luice« 

 of plants, after penetrating; through the cuticle. The wings, where twey ex- 

 ist, are ample, thin, easily lacerated, hyaline, crossed by a few stroog, oo- 

 oasionally coloured, ribs. Its body is {leaked at the tip^ and a little M/or« 

 it there are two short diverging tubes, through which oom« a oI«Ar sao- 

 charino Huid of the same nature as the honey-dews thai boeWtfar the* 

 foliage of the plants they infest. Their colours are varied i in Bom»f 

 sombre and opaque ; in others, prettily mottled, or coucenled by cottony 

 filaments or a scaly scurf; while some are no transparent that their inti-ra- 

 al organization can bo made the subject of microscopic iuspection. Tl«y 

 are of Hluggish habits; and their movements, except those executed on tUa 

 wing, are gradual and protracted. The species that frequent t\m turnip 

 fields are a blackish green, mealy-coated species {Aphis Brasisica;), the 

 •* smother fly " of southern agriculturists, originally found u|>on the cab- 

 iMge; and Aphis Rapes of Curtis, of a yellowish green or purplish hue, an 

 insect that, under the name of Aphis vastatar, has acouired unprecedented 

 notoriety in connection with the potato disease, which Mr Sniec, in his 

 publication, has attributed to it. 1 have not noticed it in Berwickshire, 

 but instances have been told me of fields of turnips that have suft'ered ex- 

 tensively from Aphides, which, 1 conclude, from the description given, 

 were of this species. In 1844, it appeared on the while turnip in some 

 places in East Lothian.* Aphides, of which the species are not stated, ac- 

 cording to Mr Darling of Hetton House, prevailed to " a frightful extent " 

 in the northern parts of Northumberland, in the summer and autumn of 

 1842, and the farmers in that part of the district sustained very consider- 

 able damage in cousequenccf According to an eye-witneas, •* the plant 

 chiefly attacked by them was the turnip ; though Swedes did not suffer so 

 much as the kinds sown later, probably from these two reasons : — 1. The 

 Swedes, being sown earlier, had grown too large to be so easily destroyed ; 

 2dly. On account of the property of the leaves to retain water longer than 

 those of any other turnip. Thousands of these little insects might bo ob- 

 served sitting on the under side of the leaf, which they did not 'eatf'hut 

 extracted the moisture from it in such a manner, that at the end of three 

 or four days the turnip was completely killed, and could be crumbled be- 

 tween the finger and the thumb, like scorched leaves. Between five and 

 six hundred acres of turnips were totally destroved in this way in the neigh- 

 bourhood of Alnwick and Wooler, particularly about Millfield Plain an«l 

 Flodden Field, though in the southern parts of the county, and on the 

 Scotch side of the Tweed there were none to be seen, or, at least, so few as 

 not to be noticed."J Aphides abound chiefly in sheltered and low lying 

 fields, especially towards autumn in close and sultrv seasons ; loving lux- 

 uriant food, and a temperature uniform and genial, 'f hey swarmed in 1846 ; 

 during 1848 they were scarcely to be observed. They usually reside ou 

 the under side of the leaves, whence they are reached with difficulty j 

 though applicatiors of soot, salt, or quicklime, would probably check, if not 

 wholly destroy, them. The Aphides are the prey of the larvae of many 

 other species of insects, which either deposit their eggs in living individu- 

 als, or devour them wholesale. The latter oflice is performed by a slug-like 

 grub, from which a beautiful banded flj' {St/rphns »p.), often seen hovering 

 near infected plants, is produced ; and likewise by the larvse of the common 

 spotted Lady-birds {Corrinellm). Their production, however, is so amazing, 

 tijat the presence of their parasites, or even the thinning ot their rau*k8 by 

 birds, is little felt ; those that perish by these means being replaced by others, 

 which otherwise would have ptrished of inanition. For the correctness of 

 this view, suggested by Mr Walker, who more than any other British 



* Report of the Scotsmun newspaper, for August, 1844. 



t Berwickshire Naturalists' Club's rroceedlngs, ii., 11. 



\ Mr 0. Clai ke. in the Zoologist roi 1843, 1'l^ 12&. 



