ECONOMIC ENTOMOLOGY. 25 



The symptoms of the disease are that shortly after mid- 

 summer the larva has an ashy appearance, and later becomes 

 greenish milky. 



After death, which occurs in a few hours, the body dries 

 or shrivels up and en being touched crumbles to pieces. 



Professor S. A. Forbes, the State Entomologist of Illi- 

 nois, has been making a series of experiments, by trying to 

 breed the bacteria of this disease in distilled water, and 

 then to clear an infested field by communicating the bac- 

 teria to some of the larvae. The success of the experiment 

 has not yet become established, but it is hoped that it soon 

 will be. 



The larvae may be destroyed by sprinkling them with a 

 mixture of pyrethrum and water, which has the advantage 

 of killing the worms, and at the same time it is perfectly 

 harmless in its effects on the human race, so that no evil 

 results come from sprinkling it on the cabbages. A child 

 with a net can do a great deal of good by capturing the 

 butterflies. 



THE SOUTHERN CABBAGE BUTTERFLY 



(Pieris j/rotodice.) 



is a native of this country, and does not differ essentially in 

 the habits from the European or imported species, but it is 

 far less injurious. 



Fig. 27. Southern Cabbage Butterfly (female). (One-fourth natural size.) 



