382 



Observations on the Turnij:) Saw- Fly. 



pubescence which clothes some of their members, and probably 

 from an oily exudation, can easily recover when they fall into 

 pure water and escape from its surface, yet when they are forcibly 

 washed off the plants and get entangled with the soil, as lime, 

 clay, or any other earthy matter, especially in cold weather, the 

 greater portion of them would be rendered incapable of doing 

 further mischief. On the sea-coast, where they have generally 

 first appeared, salt water from the sea might often be advan- 

 tageously employed; and the dusting of finely-pounded salt over 

 the field would do great service, if it were scattered whilst the 

 turnips were wet from rain or heavy dews. Mr. Newport justly 

 observes that sea-water or salt and water is likely to prove useful 

 for two reasons — " first, from the known pernicious effect of saline 

 matters in solution upon most young insects; and next, the 

 circumstance of a greater amount of cold being produced during 

 its evaporation, whilst the means applied as a remedy for the 

 insect would on most lands prove beneficial to the soil, and 

 hasten the growth of the crops." 



Drawing a cart-rope over the turnips to shake off the cater- 

 pillars is sometimes very effective, but not always to be depended 

 upon. Mr. Sells says that two men were employed in the middle 

 of September to sweep 6 acres of turnips at Kingston, with an inch- 

 rope about 30 feet long ; it took them one hour each time, and was 

 daily repeated for four days with great success, vast numbers of the 

 larvae being found dead under the turnips. This operation ought 

 to be performed in the evening, taking advantage, if possible, of a 

 wet day ; and should the larvae not have arrived at maturity, so 

 much the better, as all those that are moulting must perish. A 

 better plan perhaps is to take an axle-tree connecting two wheels, 

 and lash some branches of the green furze* to it at such a height, 

 that they would brush the turnips without pulling them up by the 

 roots ; this not only has the same advantages as the rope, but great 

 numbers of the caterpillars are wounded and destroyed by the 

 thorns ; if furze cannot be readily procured, branches of the fir- 

 tree or hawthorn may be substituted. A hurdle bushed with 

 smooth boughs and drawn down the rows has also had a good 

 effect, but it must be repeated two or three times. 



The elder has long been celebrated for its virtues in repelling 

 the attacks of insects, and in the canker years it has been tried in 

 various ways, sometimes with success ; but possibly many other 

 trees, employed in the same manner, would have proved just as 

 serviceable : for Mr. Marshall's experiments clearly showed that 

 the elder is neither noxious nor disagreeable to the black cater- 

 pillar ; even a turnip-leaf which had been ivhipjoed with the elder. 



* The Ulex EuropcEus, called in some counties gorze or gorse and whin. 



