150 NATURAL HISTORY 



is also passed over by late writers; and that is the 

 Curvicauda of old Mouffet, mentioned by Derham in his 

 Physico-Theology, p. 250 : an insect worthy of remark 

 for depositing its eggs as it flies in so dexterous a 

 manner on the single hairs of the legs and flanks of 

 grass horses 4 . But then Derham is mistaken when he 



fairer prospect for a crop of turnips had not been seen for many years, 

 were ploughed up in consequence of their attacks. Their ravages were 

 preceded by the appearance of the yellow fly in immense numbers ; and 

 it was believed, as they occurred most freely on the coast, that they 

 arrived from across the ocean : some fishermen even declared that they 

 saw them come in cloud-like flights. But there is no sufficient reason 

 for attributing to them other than a home origin. They are seen here every 

 summer; although it is only occasionally, when circumstances combine to 

 favour an extraordinarily rapid growth and frequent broods among them, 

 that they are so numerous as to become extensively destructive. 



Against the attacks of the black caterpillar no preventive has yet been 

 suggested. When it prevails the most effectual means of keeping it 

 under is by freely sprinkling the infested fields with lime, and renewing 

 the sprinkling as often as the fine powder may happen to be carried away 

 by the wind. The same process appears also to have been the most 

 successful that has yet been resorted to against the attacks of the little 

 enemy of every season. It is strongly recommended in a report on the 

 ordinary turnip-fly, published in 1834 by the Doncaster Agricultural 

 Society, as the result of a very extensive correspondence, instituted with 

 the especial view of collecting, from all parts of England, information on 

 a subject of so much importance to the agriculturist. . T. B. 



4 It is by no means surprising that Gilbert White should have believed 

 that the horse bot-fly had been omitted from his works by Linnaeus; for 

 it could scarcely have occurred to him to look for it, either in the Systema 

 Naturae or in the Fauna Suecica, under the very inappropriate name 

 of CEstrus Bocis: yet by that name he would have found it described 

 in both those works. The habitats assigned to it by Linnaeus, the 

 stomach of the horse and the back of kine, show that he confounded 

 together two distinct insects, the maggots of which infest the several 

 situations referred toby him. The maggots of the one, known by the names 

 of wormals or warbles and sometimes by that of bots, are found beneath 

 the skin of cattle: these are the larvae of the true (Estrus Boris, the 

 perfect fly of which was probably unknown to the great Swedish natu- 

 ralist. The maggots of the other, known, in common with those of some 

 other species, by the name of bots, are found with the larvae of those 

 other bot-flies in the stomachs of horses. The one whose habits are 

 described by White, may be called the spotted-winged bot-fly : it is 

 described by Linnaeus under the erroneous name of CEstrus Boris ; by 

 Mr. Bracy Clark under the name of Oestrus Eqiti ; and is, in modern 



