On the Insects affecting the Turnip Crop. 



205 



and when tlie plants came up, and the fly was observed attacking 

 them, lime-dust was thrown over them, so that many of the plants 

 were quite white with a coat of it ; after which as many flies were 

 found upon those as upon any that were free, and they were even- 

 tually devoured. This is again quite at variance with the 

 opinion, that repeated dustings of ashes and soot, Avhen the plants 

 are wet with dew, will keep off the fly, and prevent their feeding. 

 In another place he states, that the upper part of a field in a 

 sheltered situation, with a south aspect, which had been sown 

 with barley, was well dressed with lime, and sown early in May 

 with whitestone turnips, which were destroyed as soon as they 

 appeared above ground ; the land was sown again, and harrowed, 

 the surface being thickly strewed over with wood-ashes; the 

 plants were, however, devoured as rapidly as before. 



The growth of the turnips being stunted by too frequent repe- 

 titions, they become fingery on light sandy soils, and are then 

 more likely to fall a sacrifice to the fly. A good coat of clay or 

 chalk has the effect in Norfolk and Suffolk of invigorating the 

 land, and giving it the power of again producing good crops once 

 in four years. The culture of mangold-wurtzel is well deserving 

 the attention of the farmer^ when the land gets tired of turnips ; 

 and it has the additional recommendation of not encouraging the 

 increase of the turnip-beetles. As it is quite certain, I should 

 say, that the beetles are attracted by scent, it appears to me likely 

 that, if a field of turnips were planted round with a belt of mangold- 

 wurtzel^ the turnips might escape their attacks, if not entirely, to 

 a very considerable extent ; especially when the insects are be- 

 lieved to come from a distance ; for at the early stage of the plants 

 a few hours of respite may be of vital importance. The Swedish 

 turnip, or Ruta-haga, whether it be a hybrid produced by the 

 turnip and cabbage, or a distinct species, has not the strong scent 

 at an advanced period which is so perceptible in the English 

 turnip when in rough leaf; and if there be as marked a difference 

 of smell in the seed-leaves, it would give the former a decided 

 advantage in exposed situations, where the beetles are attracted 

 from distant localities : being sown in May or June, however, is, 

 I conceive, not a recommendation, as I believe that to be a period 

 of the year when the first principal brood is generally at its 

 maximum, as the second is in August or September; but the 

 temperature of the seasons may in this respect make a variation 

 of a fortnight or three weeks on either side of the average : how- 

 ever this may be, it is admitted on all sides that the beetle is 

 weakest in July. 



I fear, on the other hand, that no early sowing can insure the 

 turnip-crop ; for as the beetles hybernate, the same warmth and 

 sunshine that m^ake the seed vegetate will bring the swarms of 



