THE FARMERS' REGISTER. 



421 



crop after all traces of the insects themselves 

 have disappeared. Great disputes have occurred 

 whether the eg2s of the insects are deposited 

 on the seed, in the manure, or in the earth ; but 

 as these are matters ol' published noiorieiy, I con- 

 ceive they have no riifht to be canvassed in an 

 account like this. Thus much may be said, that 

 the <jeneraliy received opinion now is, that the 

 e»jgs are deposited on the leal, and lliat the mi 

 nute larva? leed in the niterior ol' the leaf belbre 

 they attain tlie flea Ibrm.* I am sirontfly inclined 

 to believe this Irom the fact, that generally lor a 

 week or more belbre the attacks of the fleas be- 

 come any thina; like so general as to threaten de- 

 struction to the plants, ihe latter lose their thriving 

 appearance, their growth is arrested, and it is 

 more than probable that the lar^is are then at 

 work in the interior of the leaves, which the f)lant 

 has to resist, instead of growing so rapidly as ii 

 otherwise would. A lew insects remain in the 

 perlect state through the winter ; 1 have observed 

 them on a sunny day in the begiiming of Novem- 

 ber, though their appearance after August is by 

 no means common. 



Prevention of iheir attacks may be in some 

 measure efli^cted, but any application by way of 

 cure, when they have commenced their ravages, 

 is out of the question. I have tried sulphur, lime, 

 soot, &c., without any perceptible eflect ; to pre- 

 vent, therelbre, should be the principal object. 

 Those I have lound to be most useliil as preven- 

 tives which most tend to excite the vigorous and 

 rapid growth of the plants in their early stages. 

 Thus, the rid<re or drill system, in which the tur- 

 nips are put in immediate contact with the ma- 

 nure, is most likely to enable the plants to over- 

 come an attack. Pleniy of seed is also desirable, 

 as the thicker the plants come up, the more rapid- 

 ly they grow, and the more vegetable matter 

 there is lor the fleas to ronsume. There is no 

 (ear of the crop being destroyed alter the rough 

 or secondary leaves are expanded. Another pre- 

 caution is, to keep the land clear of weeds, and 

 above all to preserve as .much as possible the 

 moisture in the soil previous to sowing in a dry 

 season. As a more remote mode of prevention, 

 the charlock, the turnips from amongst the grow- 

 ing corn, and the weeds of the cruciferous kind 

 should be kept thoroughly down, as these form 

 nurseries lor the insects before they commence 

 their attacks upon the turnips. 



2. The next insect to the attack of which the tur- 

 nip is liable is the black caterpillar, the larva of 

 the yellow saw-fly (^j^ihalia ceniifoiiai). In 1835, 

 the north of England was visited by these depre- 

 dators to a most alarming extent ; in the follow- 

 ing year they penetrated into Yorkshire, and in 

 small numbers into some parts of Scotland. The 



* The habits of the larva in this respect are no 

 longer matter of conjecture. In a memoir on this in- 

 sect, published in the 2d volume of the Transactions 

 of the Entomological Society of London, Mr. H. Le 

 Keux has demonstrated that the larva; feed on the 

 interior of the leaf, consuming its pulpy substance 

 in the same manner as the mining caterpillars of va- 

 rious small moths, and certain dipterous larvse. It 

 undergoes its transformations in its subcutaneous gal- 

 leries. The larva is figured in the memoir just al- 

 luded to, as well as in Westwood's Introduction to the 

 Modern Classification of Insects, vol, i., p. 3S3. — Ed. 

 Farmers' Magazine. 



attack in this year, though severe, was, Iiowever, 

 less destructive than that of the preceding. The 

 caterpillars are usually observed when the plants 

 are of about three weeks' growih. In iheir early 

 siages the caterpillars invariably attach ihen)- 

 si'lves to the under side of the leaf. They are 

 aliDUt one-fourth of an inch long, and of a whit- 

 isligray color, and not very easily discerned. 

 They change their skin at least three times 

 during their exisience in the cater|)illar slate, and 

 afier each cnange appear lighter colored at first, 

 but in a few hours become a brighter, deeper 

 black, destitute of hair, but the body co'isiderably 

 wrinkled. About twenty-one days alter the ca- 

 terpillars have emerged they burrow into the 

 earth, and there (orm a cocoon or case, remain in 

 it twenty days, and then emerge a yellow fly; 

 airainto breed and furnish a fresh supply of cater- 

 pillars. This fly is furnished with a peculiarly- 

 shaped oviposiior of a saw-like construction, vvitli 

 which she punctures the edges of the turnip-leaf j 

 and deposites her egL's singly. A portion, how- 

 ever, of the caterpillars which disappear remain 

 in the cocoon until the following summer, to pro- 

 vide a supply of caterpillars lor the succeeding 

 year. I have bred them, and led them in a glass 

 jar, and watched the whole of their habits and chan- 

 ges, and I know of no insect which attords great- 

 er facilities for observation than the one in question. 

 The attack is solely confined to the leaves of 

 the plant. They consume the whole of the cel- 

 lular texture of the leaves, and nothing but the 

 fibres remain. No plant can resist this, and the 

 shortness of the work of destruction of as fine a 

 crop as ever appeared above ground is almost 

 incredible. I have observed as many as twenty 

 caterpillars upon a single plant, and perhaps not 

 one plant occurred in the field without some 

 caterpillars upon it. 



By way of prevention little can be done, as 

 the only warning of a visitation given is ihe ap- 

 pearance of the yellow flies, which generally pre- 

 cede the caterpillars the most of a fortnight. I 

 always instruct my turnip-hoers to leave their 

 work in order to cLase and destroy every fly they 

 see of this description. In 1S37, owing principal- 

 ly to this precaution, I believe my fields escaped, 

 while some in the same parish were more or less 

 consumed. When the attack has commenced 

 the hoe ought immediately to be stopped. Ducks 

 of about three weeks old should be turned into 

 the field ; if they are much older they will eat 

 the plants and reject the caterpillars. Hand-pick- 

 ing should also be resorted to. I saved a field of 

 fii^ht acres in the "canker year," (1S36,) by em- 

 ploying children to gather them, and put them 

 into closed vessels. I gave these sixpence per 

 day, and the numbers they gathered were enor- 

 mous. I destroyed them by pouring boiling wa- 

 ter upon them, which was instant death, though 

 they will live lor an indefinite period in cold water 

 — it seems to elide from their oleaginous skin. 



3. The next insect which the turnip crop is 

 liable to sutler from is the wire-worm. A de- 

 scription of it is scarcely necessary, for, from the 

 unlettered peasant to the scientific entomologist, 

 every person who knows any thing of rural con- 

 cerns is familiar with it. In order, however, to 

 describe exactly the individual insect I mean, 1 

 may observe that the grub is of a yellow color; 

 its body is nearly cylindrical, and composed of 



