54 Observations on Insects affecting the Turnip Crops. 



ochraceous also : wings iridescent, the nervures light brown : 

 stigmatic spot long and yellowish; apical cell somewhat oval; 

 furcate cells elongate-trigonate ; terminal one short : tips of 

 thighs^ shanks, feet, and claws, black (fig. 1). Female — bright 

 green, shagreened : horns fuscous, except at the base : eyes, tips 

 of shanks, and feet^ black (fig. 2). 



Abundant beneath the leaves of the English turnip the whole 

 of July, &c. It is at once distinguished from the other species 

 by its long tubes and small apical cells of the wings. 



2. Aphis dubia, Curtis — the Black-spotted turnip-leaf plant- 

 louse. 



Female ? — dull darkish green, shagreened : antenna? shortish, 

 third joint ochraceous, the following fuscous : rostrum short and 

 stout : eyes, ocelli, and two large patches on the collar, black : 

 each segment of the abdomen has a more or less complete trans- 

 verse black stripe, interrupted down the middle ; the tubes are 

 slender and longish, the tail is banded with black, and the conical 

 apex is of the same colour (fig. 4). 



Found, the end of July, beneath the turnip-leaves, with the 

 former species. 



3. Aphis BrassiccT, LiniKSus — the Cabbage and Swedish- 

 turnip-leaf plant-louse. 



Male — generally pea-green : horns setaceous, longish, and 

 black ; as well as the head, collar, and disc of thorax : several 

 blackish bands, more or less perfect, across the body : tubes short 

 and stoutish, black at the base : wings iridescent, stigma pale- 

 green, nervures strong, piceous, apical cell large, and the first fur- 

 cate one wider than in A. rapoB : legs black, base of thighs 

 green (fig. 5). Female — slightly mealy, generally of a yellower 

 green than the males : third joint of antennae ochraceous, fol- 

 lowing black : eyes, two large spots on the crown, and one on 

 each side of the collar, black : abdomen very large and heavy : 

 spiracles, several dots upon the back, and a few transverse streaks 

 beyond the middle, black: tubes short and black, as well as the 

 legs ; base of thighs, greenish (fig. 6) . 



As far as my own observation goes, the swedes have suffered 

 most from the Aphides ; the under-sides of the curled leaves be- 

 ing sometimes densely covered with them, of all sizes. The old 

 wingless females are seen resting, in August, September, and 

 October, surrounded by their young broods, with here and there 

 a winged male walking lazily over his kindred. The leaves are 

 frequently at the same time grey with mildew ; but that is a dis- 

 tinct disease.* I may observe that I have seen myriads of Aphis 



* It is said that, in a very dry autumn, early-sown turnips seldom escape 

 the mildew, which is a species of fungus, forming a whitish powder over 

 the leaves, and readily brushing off : the leaves thus affected soon become 



