EXPERIMENT STATION BULLETINS. 



167 



scrapes its way all through the tissue, forming tunnels or channels, 

 and causing the root to rot. Sometimes several maggots attack a single 

 root. In about three or four weeks, the maggot becomes full grown, 

 then being about one-third of an inch in length. It then changes to a 

 pupa, the larval skin becoming papery and forming a shell, inside of 

 which the change occurs. After a short time, the adult fly cracks open 

 the shell and emerges, and a new batch of eggs is laid. The worst 

 injury is done to the young plants, before they attain much size. There 

 are several generations each year. The winter is said to be passed for 

 the most part, at least, in the pupal condition, although it is likely that 

 some of the adult flies hibernate in sheltered places. For a minutely 

 detailed account of this insect consult Bui. 78, of the Cornell Experi- 

 ment Station by Professor M. V. Sliugerland. 



>< 



Fig. 16. — Diagram showing method of 

 cutting. After Sliugerland. 



Fig. 14. — Card of tarred building-paper 

 ready to place on stem of cabbagte. 

 After Sliugerland. 



Fig. 15. — Tool for cutting 

 cards of tarred building 

 paper. Alter Slingerland. 



REMEDIES. 



Control of the cabbage root-maggot is best obtained by preventing 

 the laying of the eggs, by means of a repellant. Professor Slingerland 

 in his exhaustive experiments secured the best results by placing a 

 small hexagonal piece of tarred building-paper, about two and one-half 

 inches in diameter, about each plant shortly after setting time. Each 

 piece or pad had a slit running to the center and a star-shaped cut at that 

 point. It was pressed close to the ground and put on squarely so that 

 it afforded almost complete protection to the crown of the plant, thus 

 preventing the female from depositing her eggs. These pads were cut 



