April, '11] 



schoene: cabbage maggot. 



215 



these adventitious buds, and their presence is partly understood 

 because of the great numbers of these buds or sprouts that appear 

 after the cabbage is cut. It is probable that the adults are attracted 

 to the "sprouts" because of the tender growth. Rough estimations, 

 based on the examination of 50 to 100 plants in each of a number of 

 fields indicate from 300 to 1,500 maggots per acre. 



Effect of Plowing on Pupae 



For this experiment a seed-bed badly infested with maggots was 

 selected. The injury to the roots of the plants in this bed was so 

 general that the entire planting was abandoned by the owner. The 

 soil was very light and sandy, and the plot on which the bed was 

 located had just enough slope to carry off the surface water. Two 

 portions of the bed in which the injuries seemed equal were chosen, 

 and on June 23d one was plowed to the depth of six or seven inches 

 and harrowed. The next day a small cheese-cloth screen 6 x 24 feet, 

 such as is used in this locality for the protection of seedling cabbages, 

 was erected over each part. (Bui. 301, N. Y. Sta.) As the flies emerged 

 from the soil they were collected, the dates and numbers taken being 

 as follows: 



TABLE IV 



THE DATES OF APPEARANCE AND NUMBER OF FLIES COLLECTED FROM PLOWED 

 AND UNPLOWED SOIL AT SENECA CASTLE, N. Y., DURING 1909 



Date 



Unplowed 



Plowed 



As shown in the above table only about 27 per cent as many flies 

 emerged from the plowed as from the unplowed plot. 



1 Numbers estimated. 



2 About 10 per cent of the males in these collections were P. fusciceps. 



