82 



REPORT ON A TRIAL OF TARRED FELT "DISCS" 

 FOR PROTECTING CABBAGES AND CAULI- 

 FLOWERS FROM ATTACKS OF THE CABBAGE- 

 ROOT FLY. 



By J. T. WADSWORTH, 



Research Assistant in the Department of Agricultural Entomology, 

 Manchester University. 



(With Plate XIV.) 

 CONTENTS 



PAGE 



(1) Introduction and Historical Remarks .... 82 



(2) Description of the experiments ..... 83 



(rt) With Cabbages 85 



(6) With Cauliflowers 86 



(.'}) I'recautions to be observed in ap])lyiny tlic discs, and 



other remarks . . ..... 89 



(4) Literature ......... 91 



(5) Description of Plate ....... 92 



Introduction. 



The present investigation has been carried out at the suggestion 

 of Dr A. D. Imnis. He has displa^yed a keen interest in the progress 

 of the experiments and I have had the benefit of discussing with him 

 any points that arose from time to time. 



The expenses entailed during these experiments have been met 

 from the annual grant of the Dept. of Agricultural Entomology, 

 Manchester University. 



It is a fact only too well known to most growers of cabbages, 

 cauUflowers and related vegetables that large proportions of their 

 crops are frequently lost owing to attacks of the Cabbage-root Maggot, 

 the larva of Chortophila hrassicne. A very large number of remedies 

 have been devised with the object of either destroying the maggots 



