268 The Spraying of Plants. 



on the crop. The first brood should be exterminated by repeated 

 and thorough applications. 



Cabbage Root-maggot (Phorbia Brassicce, Bouche). Descrip- 

 tion. The adult insect is a two-winged fly which bears much 

 resemblance to that so commonly found in and about dwelling- 

 houses. It is considerably smaller, however, and the wings 

 fold more closely together. 



The adult flies appear during April and early May. Eggs 

 are laid about the base of the newly set plants, in some cases 

 several hundred being found about a single plant. These ap- 

 pear to hatch in about a week, depending upon the condition of 

 the weather. The young maggots generally first attack the 

 young roots, burrowing along their surfaces, until finally the 

 root is destroyed. The main roots are then attacked, and later 

 the stem of the plant may be entered. In this manner a crop 

 is soon rendered worthless. There appear to be two, and pos- 

 sibly three broods each year. 



Treatment. The cabbage root-maggot has for years been 

 causing serious losses to cabbage growers, and although about 

 seventy methods of destroying the pest have been recommended, 

 only few have much merit, showing that the enemy is a difficult 

 one to deal with. Pieces of tar paper fitted closely about the 

 young plants at the time of setting, or immediately after, are 

 very effective in preventing the flies from laying their eggs. 

 As the insect works upon many weeds, and also upon other cul- 

 tivated plants, this method does not destroy the pest, but drives 

 it to other quarters, from which future supplies may at all times 

 come. Another and better plan is to inject about a teaspoon- 

 f ul of the bisulphide of carbon just underneath the plant, avoid- 

 ing contact with the roots as much as possible. In severe cases 

 a tablespoonf ul may be used to advantage. One application, if 

 made when the maggots are first seen in May, should be suffi- 

 cient. After applying the liquid, press the soil about the plant, 

 to prevent, as far as possible, the escape of the fumes. 1 



CABBAGE-WORM. 



Imported Cabbage-butterfly (Pieris Rapce, Linn.). Description. 

 Our common cabbage-worm, although a species introduced from 



1 For an exhaustive account of this insect, see Slingerland, Cornell Agric. Exp. 

 Sta. 1894, Bull. 78. 



