370 



Observations on the Turnip Saw-Flij. 



frozen ; and it is probable that the thaw acted as beneficially^ by 

 subsequently destroying the remainder, either by decomposition 

 or rendering the earth too wet and cold to bring them to ma- 

 turity. They did not, however, finally take their departure, 

 for, if I be not in error with regard to the date, I find one instance 

 recorded of a brood making its appearance the year following at 

 King's Weston, near Bristol. But I will transcribe Mr. Miles's 

 own account, as it is interesting for several reasons : — The 

 turnip- crops went on together very well until the 8th of July, 

 when I perceive by my farming-book that the black caterpillar 

 first appeared. Its ravages were extended to both crops indiscri- 

 minately ; as usual, however, with me, it attacked the field in 

 patches, making sad havoc Vv^ith the swedes, and entirely skipping 

 over four rows of mangold-wurzel, which had been placed between 

 the swedes and red-rings by way of experiment — to ascertain 

 whether that plant could escape when surrounded by a crop in- x 

 fected by the caterpillar." * 



Before entering upon the history and economy of the turnip 

 saw-fly, a few remarks upon the tribe to which it belongs will not 

 be uninteresting, for amongst the hymenoptera, the order in which 

 it is included, there is no family which does so much mischief to 

 plants as the tenthredinidae ; indeed a very large portion of the 

 innumerable ichneumons and sand-wasps are of essential service, 

 being the parasites which infest and devour noxious insects. 

 Neither trees, bushes, gardens, nor fields are, however, exempted 

 from the attacks of the caterpillars of the saw-flies. The largest 

 species feed upon the birch, willows, and white-thorn, y The 

 coniferae, or fir-trees, are stripped of their leaves by Lophyriis 

 rufus, pallidus, and pini.\ Fruit-trees, as the peach, plum, cherry, 

 and the pear especially, suffer from a bottle-green shining slug- 

 like larva, with several other species, and amongst them a Lyda.^ 

 Gooseberry and currant bushes are often entirely stripped of 

 their leaves, and the fruit rendered small and unsaleable, by the 

 depredations of Nematus tri?naculatus ; || and our beautiful roses 

 do not escape the ravages of several species, amongst them Hylo- 

 toma RoscE^ and Athalla Roses, which are so nearly allied to the 

 turnip saw-fly that a casual observer would consider them to be 



* Royal Agr. Jouni., vol. i. p. 417. Experiment with Poittevin's manure, 

 by Wm. Miles, Esq., M.P. I have since learned that a crop of tm-nips 

 belonging to the Rev. C. Clarke, of Hulver, in Suffolk, was seriously in- 

 jured in 1838- 



t Vide Curtis's Brit. Ent., plates 41, 47, 49, 89, 93, and 97, where dis- 

 sections and descriptions of six genera will be found. 

 % Ibid., plate 54. 

 § Ibid., plate 381. 



II Ruricola, in the Gardener's Chron., No. xxxiv. p. 548. 

 % Curt. Brit. Ent., fols. 65, 436, and 457. 



