190 PIEST ANNUAL REPOKT OF THE STATE ENTOMOLOGIST. 



shall be established. To the increasing ravages of these two species this 

 novel importation is mainly attributable. 



Preventives and Remedies. 



Various means have been suggested for controlling the depredations 

 of the cabbage-fly. Bouche, the original describer of it, tells us that 

 the plants may be preserved by dipping the roots when they are trans- 

 planted from the seed-beds, into oil or lye of ashes. 



Powdered tobacco, or the fine dust from tobacco factories, scattered 

 over the plants, is said to px'eserve them from attack. 



The use of superphosphate of lime has been advised, as a preven- 

 tive against the deposit of the eggs. 



If cabbages are not grown upon the same ground for successive 

 years, and the ground meantime thoroughly cultivated with some other 

 crop, the insect will be materially reduced in numbers. 



In the experiments at the Michigan State Agricultural College, re- 

 ferred to on p. 193, a strong decoction of tobacco was freely applied to 

 the plants, but without appreciable benefit. 



"When the attack of larvae has reached that stage of progress that the 

 plants unmistakably show it by wilting and the leaves turning to a 

 faint lead-color, all such should be promptly taken up, and the hole left 

 should be filled with strong brine or lye to destroy any of the larvse 

 which might remain in the soil. This last precaution would be unnec- 

 essary if the plants were removed by the method recommended for 

 onions (p. 178), but in that case, the accompanying ground should be 

 thrown with the plants in a deep hole made for the purpose, and covered 

 with solidly packed earth, through which the flies, if any of the 

 buried larvae should attain this stage, could not penetrate to the 

 surface. 



Watering the plants with lime water has been found to be of ser- 

 vice in killing the larvae. 



Professor A. J. Cook has recently recommended the following 

 method for the destruction of the larvae. Bisulphide of carbon is used. 

 '* To apply it, a small hole is made in the earth near the main root of 

 the plant, by use of a walking-stick or other rod, and about one-half a 

 teaspoonful of the liquid poured in, when the hole is quickly filled 

 with earth, which is pressed down by the foot. In every case the in- 

 sects were killed, without injury to the plants." Amer. Entomol., iii, 



1880, p. 2G4. 



While Professor Cook, as the result of the expei'iments of the present 

 year, believes carbolic acid to be preferable to bisulphide of carbon for 

 the protection of radishes (see p. 194), he is still of opinion that the lat- 

 ter material is the most reliable in contending with the cabbage-fly. 



