The Currant Fruit Fly. 227 



TABLE 25. 



Quantity of Potassium Cyanide Buried in Soil at Various 

 Distances from Bushes. 



Quantity ol i Number of Distance from bush 



potassium cyanide holes, poison poison was buried Kind of bush 



(oz.) ; was buried (inches) 



14 6 Wild gooseberry 



2 6 4 Wild gooseberry 



3 8 1 8 IWild gooseberry 



4 8 12 |Wild gooseberry 

 4 8 ! 18 Red currant 



No fruit flies emerged from 50 puparia buried in clay soil 

 treated with two applications of one part carbolic emulsion to 

 50 parts of water, at the rate of one-half gallon per square foot ; 

 but in the experiment previously described in which a cage was 

 placed over a currant bush and the ground was treated wath the 

 same formula, flies emerged after each application of the insecti- 

 cide. 



Use of Oils to Trap Adults. 



Recent investigations have shown that certain vegetable 

 and petroleum oils attract enormous numbers of male fruit flies 

 of different species. Pans containing pure oil or a few drops 

 of oil poured in water which partly filled the pans were placed 

 upon the ground under currant and gooseberry bushes. Each 

 oil was tested out separately so that there was no possibility 

 of the volatile parts of different oils interfering with one another. 

 The number of pans used, the number of days each oil was 

 tested and the results obtained are stated in table 26. 



