Observations on the Turnip Saw- Fly. 



383 



was eaten by them when they were confined with it in a box. 

 The benefit alluded to was derived from the use of a brush made 

 of the young straight luxuriant shoots of the elder^ about 2 or 

 3 feet long, and as thick as one's finger ; these were tied to a 

 cart-rope 20 feet long, with rope-yarn 4 to 6 inches apart. Two 

 men then took hold near the twigs, the loose ends of the rope 

 being tied together, and dragged the elder at a distance behind ; 

 of course the rope may be prepared of any convenient length for 

 the men to walk along the furrows, but 20 feet will take in a rod 

 at once. Mr. Marshall also reports another successful case. In 

 a field that was partly sown early, the saw-flies* appeared when 

 they were in rough leaf ; this portion was entirely cut off by the 

 black~caterpillars, so that it was necessary to plough and sow a 

 second time ; but the ploughing and harrowing did not kill all 

 the larvae^ for thousands were seen on the surface travelling 

 towards the portion of the field which had been late sown, the 

 plants of which were of a considerable size ; a trench was imme- 

 diately cut to divide the two portions, and two men drew the 

 elder-bushes over the turnips thrice a-day, at morning, noon, and 

 night, which employed them an hour and a half each time to go 

 over about 3 acres. This was continued for ten days, and the 

 elder was renewed three times. Whatever might be the cause, 



after looking attentively for some time among the plants, I saw 

 only two caterpillars, and so healthy a piece of turnips I do not 

 recollect to have seen ; they have been sown only three weeks, 

 yet they are now fit for the hoe."j Mr. Marshall attributes this 

 success to the complete and continued vibration of the leaves 

 given by tlie straight elder-twigs lying flat and even upon them 

 as they passed over. 



When turnips are sown in ridges a number of women have 

 been advantageously employed with live twigs, to brush the larvae 

 off, crushing them with their feet as they passed on, being 



closely followed by a man with a scuffler, set so as to cover the 

 whole space between the plants ; and by once or twice going over 

 the field was cleared." J 



It was a universal practice in Norfolk, which had generally a 

 good effect, when one portion of a field was swept off by the 

 larvae, and they were marching to a less infested portion, to draw 

 a furrow between them, deepening it into a trench. The side 

 next the part to be protected should be made, of course, perpen- 



* It is most essential for agriculturists to call these flies saw-flies, and 

 not merely " the flies," in consequence of the turnip- beetle being also called 

 the "fly," otherwise great uncertainty and confusion may be the conse- 

 quence in future investigations. 



t Abstract from Marshall's Rural Economy, p. 18. 



% Trans, of Yorksh, Agric. Soc, p. 54. 



