104 INDIRECT INJURIES CAUSED BY INSECTS. 



as H. condnna, attack and devour them ; so that, on account of their 

 ravages, the land is often obliged to be resown, and frequently with no 

 better success. It has been calculated by an eminent agriculturist, that 

 from this cause alone the loss sustained in the turnip crops in Devonshire, 

 in 1786, was not less than lOOjOOO/. 1 Much damage is also sometimes 

 occasioned by a little weevil (Nedyus contractiis), which in the same 

 manner pierces a hole in the cuticle. When the plant is more advanced, 

 and out of danger from these pigmy foes, the black larvae of a saw-fly 

 (Athalia Centifolice) , called by the fanners the "black" and "nigger" cater- 

 pillars, take their place, and occasionally do no little mischief, whole 

 districts being sometimes nearly stripped by them; so that in 1782 and 

 1783, many thousand acres were on this account ploughed up : and in 

 1835, 1836, and 1837, the injury was not less extensive. 2 The caterpillar 

 of the cabbage-butterfly (Pontia Brassica), is also sometimes found upon 

 the turnip in great numbers ; and Sir Joseph Banks informs me that forty 

 or fifty of the insects before mentioned, called by Mr. Walford the wire- 

 worm, but more probably, as there observed, the larvae of one of the tribe 

 of Brachyptera or rove-beetles, have been discovered in October just below 

 the leaves in a single bulb of this plant. The small knob or tubercle often 

 observable on these roots is inhabited by a grub, which resembles one found 

 in similar knobs on the roots of Sinapis arvensis (from which I have bred 

 Nedyus contractus, and N. assimilis, small weevils nearly related to each 

 other), and like it produces a small weevil, Ceutorhynchus sulcicollis. This, 

 however, does not seem to affect their growth. Great mischief is occa- 

 sionally done to the young plants by the wire-worm. I was shown a field 

 last summer in which they had destroyed one fourth of the crop, and the 

 gentleman who showed them to me calculated that his loss by them would 

 be 100/. One year he sowed a field thrice with turnips, which were twice 

 wholly, and the third time in great part, cut off by this insect. 3 The roots 

 are also sometimes seriously injured by the caterpillars of the moth 

 (Agrotis Segetum) before mentioned as destructive to wheat crops on the 

 Continent. Whether the disease to which turnips are subject in some 

 parts of the kingdom, from the form of the excrescences into which the 



1 Young's Annals of Agriculture, vii. 102. For a full history of Haltica Nemorum, 

 from the egg to its perfect state, see the very valuable paper of Henry Le Keux, 

 Esq., in the Transactions of the Entomological Society of London (ii. 24.), who, 

 though no entomologist or agriculturist, has by his practical good sense and habits 

 of patient and accurate observation, thrown more light on this previously obscure 

 subject than all his predecessors. 



2 Marshal in Philos. Trans. Ixxiii. 1783. See Trans. Ent. Soc. Land. i. proc. Ixvi., 

 ii. proc. Ixxviii. and the admirable Prize Essay, containing a full history of this 

 insect by G. Newport, Esq., 1838. See also the valuable papers on this insect, and 

 on the turnip-flea, in Journal of the Royal Agricultural Society of England, vol. ii., by 

 John Curtis, Esq. 



3 Trans. Soc. Ent. Land. ii. proc. xxx. A striking instance of the use of hand- 

 picking (in most cases by far the most effective mode of getting rid of insects) ap- 

 peared in the West Briton, a provincial paper, in November, 1838, stating that Mr. 

 G. Pearce of Pennare Goran had saved an acre and a half of turnips, sown to replace 

 wheat destroyed by the wire-worm and attacked by hosts of these larvae, by setting 

 boys to collect them, who, at the rate of three half-pence per 100, gathered 18,000, 

 as many as 50 having been taken from one turnip. Thus at an expense of only 

 11. 2s. 6d. an acre and a half of turnips, worth from 51. to 11. or more, was saved; 

 while as the boys could each collect 600 per day, 30 days' employment was given 

 to them at 9d per day, which they would not otherwise have had. 





