66 DISEASES OF CROPS. 



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

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

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

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

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

 to pupae 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.^ 



UniDJured 

 Roots. 



Injured 

 BootB. 



Dried 



solid 



matter. 



Albuminoids (flesh formers) 



Soluble carbohydrates and fat (fat 



producers) 



Woody fibre 



(Ash 



9-86 



71-90 



11'24 



7-00 



7 '10 



62 02 



23-25 



7-63 



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 pupal 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. Grifaths' analyses. 



