ESCULENT -ROOTED PLANTS.— THE TURNIP. 



193 



seed would only be presenting each brood with 

 a supply of food in about as regular a succession 

 as they themselves are produced. 



Burning the surface of the land is beneficial 

 where it can be carried into effect, as by that 

 means the chrysalides will be destroyed; and an 

 equally certain way is to trench the ground deep. 

 Indeed, the destruction of insects alone, were 

 no other benefit to arise from trenching, would 

 of itself be a sufficient recompense for the 

 labour incurred. Sowing the surface of the soil 

 with gas-lime two or three mornings after the 

 seed has been sown, has been recommended on 

 account of the disagreeable smell being so offen- 

 sive to the insect as to drive it away. Spirits of 

 tar, in the absence of gas-lime, would have the 

 same effect. 



Charcoal dust may also be sprinkled over the 

 plants when they are either wet with rain or 

 dew; and in small gardens the watering-pot 

 may be had recourse to to wet the foliage, 

 should neither rain nor dew fall. A temporary 

 light-frame, stuck full of green alder-branches, 

 and drawn over the crop, will discompose the 

 enemy, and a stripe of light woollen cloth, 6 

 inches in width, and covered with bird-lime, 

 tar, or any equally adhesive matter, and nailed 

 to a wooden axle attached to two 12-inch 

 wheels, and drawn over the crop, will greatly 

 lessen their numbers, as the cloth brushing over 

 the tops of the young plants will disturb the 

 fleas, and cause them to leap from the leaves 

 and become attached to the cloth; and, on 

 account of its adhesiveness, they will be unable 

 to disengage themselves. This operation, per- 

 formed about twice a day, will in general secure 

 a crop. In small gardens a piece of cloth so 

 covered and attached to a handle like a small 

 flag, and drawn over the plants backwards and 

 forwards, will have the desired effect. 



Aphis rapcB Curtis, A. nastator Smee, j4. di- 

 anthi Schrank, figs. 67 and 68, is thus weU de- 



Fig. 67. 



TURNIP APHIS, MALE. 



scribed by Mr Stephens, in the "Book of the 

 Farm," vol. ii. p. 77 : " Fig. 67 represents the 

 winged male of the common turnip plant-louse. 

 Aphis rapce, magnified. Its characters are ochra- 

 ceous ; horns moderately long, setacious ; two 

 first joints black, third ochraceous at the base; 

 head blackish ; coUar ochraceous and brown ; 

 disc of shining black ; abdomen greenish ; wings 

 irridescent ; the nervures light brown ; tips of 

 the thighs, shanks, feet, and claws black. Abun- 

 dant beneath the leaves of the common turnip 

 the whole of July, &c. It is at once distiu- 



TURNIP APHIS, FEMALE. 



guished from the other species by its long tubes 

 and small apical cells of the wings. The cross 

 lines below represent 

 the natural size of the 

 body and of the expanse 

 of the wings. Fig. 68 

 is the female of the same 

 species magnified. It 

 is bright green, sha- 

 greened ; horns fuscous, 

 except at the base; eyes, 

 tips of shanks, and feet 

 black. The small figure 

 on the left represents the 

 aphis of the natural size ; 

 and the figure below re- 

 presents one of the na- 

 tural size just excluded." 

 Rurioola, in "Gardeners' Chronicle," 1847, p. 

 21, of this insect says : " It is to be hoped that 

 the species of the aphides will be determined, 

 that it may be settled whether those found on 

 the turnip (of which there are three species), 

 the potato, the spinach, &c., be identical or dif- 

 ferent. Another object will be to ascertain if 

 the aphides actually feed upon the leaves and 

 shoots of the later plants, and breed there." 

 Of the Aphis rapce, he continues: "I do not re- 

 member ever observing it before midsummer. 

 In July it becomes abundant, and in favourable 

 seasons continues increasing until the end of 

 October, or later. The first are hatched from 

 eggs, and it is said are all females ; these bring 

 forth young until the autumn, when males are 

 produced, as well as females furnished with 

 wings. These lay eggs, which remain through 

 the winter." 



The injury done by the various species of 

 aphides, or plant-lice, is incalculable, as may be 

 well supposed when we consider that there is 

 not a plant that would seem exempt from their 

 attacks in one way or other ; and it would also 

 appear, from the investigations of some of our 

 most eminent entomologists, that almost every 

 plant has an aphis natural to it, and upon 

 which it is designed to feed. Euricola, in 

 "Gardeners' Chronicle," 1842, p. 3, of this ex- 

 tensive genus thus speaks : " There is no family 

 of insects which deviates in its habits more 

 from the general laws of nature than the aphides ; 

 for whilst it is an almost universal rule that 

 this class of animals should progress through 

 the various transformations of egg, larva, pupa, 

 and imago, the aphides have the power of evad- 

 ing three of these states by the faculty they 

 possess of producing young ; for, influenced by 

 natural causes, they are both viviparous and 

 oviparous — bringing forth young at mild sea- 

 sons, when the temperature is not injurious to 

 their tender offspring, and laying eggs in autumn, 

 which are better calculated to resist the cold of 

 winter. But this is not the most curious ano- 

 maly in their history, for a succession of young 

 aphides can be produced without the presence 

 of the male insects. For instance, as soon as 

 an aphis is bom, if it be taken away and 

 placed upon a plant, under a glass, where 

 nothing can possibly gain access to it, it will, 

 notwithstanding, produce young; one of which. 



