368 



Observations on the Turnip Saw- Fly. 



at this time^ as no notice seems to have been taken of them in 

 1834. 



But 1835^ which was an unusually dry summer, might correctly 

 be designated the " Canker-year/' for they then seemed to have 

 reached their maximum. Our journals and periodicals teemed 

 with the ravages of the black caterpillar ; and in walking through 

 the turnip-fields the most casual observer must have been struck 

 by the mere skeletons which the leaves often exhibited, the fibres 

 only remaining, the membrane being entirely consumed. From 

 the middle of August to the 20th of October, at which time they 

 were full-grown, I observed them feeding on the leaves of the 

 turnips.* In September in many districts the mischief ceased ; 

 and some farmers, who sowed for turnips again immediately after 

 the first rains, were as successful as the lateness of the period 

 would admit.-}- In the south of England the second brood hatched, 

 but in the north the weather set in cold, and no second brood 

 came to maturity ; seven-tenths, therefore, probably perished. J 

 On a farm at Coomb-bottom, near Kingston, in Surrey, the tur- 

 nip-fields suffered considerably ; and in July Mr. Manning § had 

 24 acres of English turnips quite destroyed at Elton in Bedford- 

 shire^ except about 2 acres, which were not hoed out. On 

 Saturday morning," he says, " I first noticed the caterpillar very 

 numerous, about three weeks after the turnips were up, growing 

 luxuriantly and looking well ; on Monday that part of the field 

 which had been hoed about four days was entirely destroyed, and 

 so they went on with this work of destruction, which was the most 

 complete I ever saw." I then stopped the man hoeing the two 

 acres that were left, and which came to a good crop." || The 

 swedes close by the side of the white turnips were not touched. 

 Early in July the fly was universally abundant, and about the 

 middle of that month they were showered down in clouds at 

 Godalming.^ I did not notice the fly in any great numbers 

 until August and September, but I have found them as early as 

 the 29th of March, and as late as the middle of October ; I first 

 observed them in abundance in a potato-field at Battersea, and 

 afterwards in a field near Heron Court, Hants.*'^ Mr. Saunders 



* Curtis's Brit. Ent, vol. xiii. fol. 617. 



t Observations on the Economy of an Insect destructive to Turnips, by 

 W. Yarrell, Esq., in the Trans, of the Zool. Soc, vol. ii. p. 50. 



% Report on the Natural History of the Black Caterpillar, by M. M. Mil- 

 burn, Esq., in the Journal of the Yorkshire Agr. Soc, p. 49. 



§ Transactions of Entom. Soc. of London, vol. ii. p. Ixiv. 



II It is remarkable that in a field of Mr. Goodlake's, at Wadley, near 

 Faringdon, the unhoed part of a crop of swedes escaped exactly in the same 

 manner. — Ph. Pusey. 



^ Entomological Magazine. 



Curtis's Brit. Ent., vol. xiii. fol. 617. 



