Oil the Insects affecting the Ttumip Crop. 



201 



often too slow in its operation to secure immediate relief; the 

 farmer must, therefore, devise means, if possible, for the more 

 speedy destruction of the enemy. 



The beetles are seldom found in shady places, except during 

 the winter season, and they cannot bear cold and wet, which are 

 great protections against their increase ; it consequently follows 

 that warmth and sunshine are far more favourable to their multi- 

 plication, and in such seasons they are most to be dreaded. 

 Showery weather, after a long drought, and cloudy days with 

 gleams of sunshine, also render them abundant,* as such seasons 

 do the greater portion of insects, bat in a few instances they have 

 been known to do much mischief even in cold weather. 



That the turnip-beetle is endowed with an acute and powerful 

 sense of smelling, is proved by his flying against the wind, and 

 deserting all other plants as soon as a turnip-crop appears in his 

 neighbourhood. Mr. Le Keux says, that in May, 1836, when 

 the thermometer was at 75° in the shade, during a south icind, 

 great numbers were on the wing, and all proceeding southward ; 

 and again, that eight acres, forming the summit of a hill in Devon- 

 shire, were sown with turnips, and when the young plants were 

 just rising above the ground, the wind being for more than a w^eek 

 at south-east, wafting the scent to the north-west, they were so 

 destroyed on this side, that nearly an acre was bare, whilst the 

 south-east side was not touched, until the plants had attained a 

 size to render the attacks of the beetle of little consequence. 



From what has been stated, it appears that no season will secure 

 us entirely against the attacks of the turnip-beetle, and that no 

 soil is considered safe from them is evident upon the best testi- 

 mony ; it is very destructive upon strong lands, and not less so on 

 light ones. Neither is the period of their attack limited, for as 

 one pair of insects may produce five or six broods in a season, 

 there is a constant succession, which renders any plan for extir- 

 pating the beetle in any of its three early stages scarcely practi- 

 cable. As the turnip when in rough leaf is not in any danger 

 from the attacks of the beetle, it is evident that our first care 

 must be to preserve the young plants and this can only be done 

 by the preparation of the soil, or using such speedy means the 

 instant the beetles appear, as will destroy or drive them away. 

 The primary object will be to discover the best manure for that 

 purpose, and a dressing that will render, if possible, the soil 

 obnoxious to the insect. 



It has been correctly said, " that the manure which most effect- 

 ually promotes the growth of the plant vnl\ be the best defence 



* A field of turnips is stated to have been destroyed by the fly in a few 

 hours before a thunder-storm at Rockingham. 



p2 



