Observations on the Turnip Saw -Fly, 



369 



states that he never witnessed so great a destruction in turnip- 

 fields by the black caterpillar as he did in August near Dov er. 

 Very few fields had escaped, although some were less damaged 

 than others^ and the ravages were not confined to particular spots, 

 but were evident in places far apart; that in many instances 

 scarcely a vestige of green remained, and the tendrils and nerves 

 which they at first refused became in the end necessary for their 

 subsistence. He adds, In a field at the back of the Castle, 

 which w^as half planted with Swedish turnips and the other half 

 with the common kind, the former were untouched, but the latter 

 greatly injured, although separated only by a furrow, the plants 

 touching each other."* In Buckinghamshire the blacks v/ere so 

 abundant and destructive that a meeting of the farmers was con- 

 vened to consider the best mode of cure ; and it was stated that 

 the swedes had suffered equally with the others. At Compton, 

 in Surrey, a turnip-field of 8^ acres was completely demolished; 

 and a thunder-storm, accompanied by heavy rain, destroyed 

 myriads of the larvae, so that basketsful of the blacks might have 

 been swept up the following morning. 



At Long Ditton, Ham, and Guildford, their ravages had been 

 equally severe ; | indeed it was difficidt, perhaps, to find a turnip 

 country that had not been visited by these black armies ; even as 

 far north as the county of Durham they had proved very injurious 

 to this crop ; and in Essex, Bucks, Kent, Sussex, Hants, Wilts, 

 Dorset, and Somerset, the turnip-crop was altogether a failure, for 

 the produce of a second and even a third sowing was consumed by 

 them. 



In 1836 less was heard of them, yet in August I saw the flies 

 coming out of the ground in myriads in a ploughed field in the 

 neighbourhood of Bristol, where potatoes had apparently been 

 grown; and a great many hundreds of acres were destroyed in 

 Norfolk. Mr. Manning also, of Elston, had about 70 acres of 

 swedes more or less infested, but not one was to be seen on the 

 English turnips ; and he says hoeing increased them a thousand- 

 fold. 



In 1837 the only notice seems to be from Mr. Sells, who says 

 that near Arundel, in Sussex, the turnip-fields in July were in 

 some places completely laid waste. 



Thus their attacks became gradually enfeebled, when the in- 

 tense cold of January, 1838, arrested their increase; the severe 

 frost, unaccompanied by snow, left the ground exposed, so that 

 the inmates of all those cocoons that were not deeply buried were 



* Notice of the Ravages of a Black Caterpillar, &c., by W W, Saunders, 

 Esq., in Trans. Ent. Soc, vol. i. p. Ixxvi. 



t Vide a communication by W. Sells, Esq., in Trans. Ent. Soc , vol. ii. 

 p. Ixxviii. 



VOL. II. 2 D 



