06 



DISEASES OF CROPS. 



swedes and turnips. The larvsB cause gall-like excres- 

 cences (rig. 28 A) to grow upon the surfaces of turnip 

 " roots." When the larvse have attained maturity, they 

 are provided with powerful jaws, which are used for gnaw- 

 ing a way out of their temporary abode. The larvse turn 

 to pupse in the soil, where they remain about twenty-eight 

 days, enclosed in " earth-cases." The perfect insect is of 

 a blackish hue, and the elytra are marked with a number 

 of stripes and dots. 



This weevil greatly reduces the quality of the roots, as 

 the following analyses show : — 



Analysis of Turnip Roots.i 



1 Albuminoids (flesh formers) 

 Soluble carbohydrates and fat (fat 

 producers) ..... 

 Woody fibre 

 Ash 



The above table shows that the injured roots contain! 

 smaller percentages of albuminoids and soluble carbo-| 

 hydrates than the uninjured roots. 



It is stated that, in both the larval and jDupal stages, 

 this weevil is capable of enduring a temperature many 

 degrees below the freezing-point of water. 



Prevention. — (1) " Regular rotation of crops, generous 

 and clean cultivation, and the free use of lime or gas-lime, 

 will prevent this weevil from doing much harm." (2) 

 " Galled portions of roots which are left by sheep should 

 be burned." 



' Dr. A. B. Griffiths' analyses. 



