378 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



high as the diameter of the stem will admit them. They also bore 

 into the branches, and occasionally a short distance into the leaf- 

 stalks. ... In many cases the leaf-stalks are killed or are so 

 injured that they part from the stems when the latter are pulled 

 up; and again, the stems, being so closely tunneled, often part above 

 the middle, even dropping over, though not handled." The larvae 

 complete their growth in about three weeks, cut their way out of 

 the stalks and enter the earth, where they form small earthen 

 cocoons just beneath the surface. In these they transform to 

 pupae, from which the beetles emerge in about a week. The beetles 

 are common in the middle of June at Washington, but disappear 

 late in the month. 



A fortunate fact is that " cabbage appears to be one of the last 

 plants attacked in the field when any other palatable crucifer is 

 obtainable. The beetles not only greatly preferred hedge mus- 

 tard (Sisymbrium officinale), and wild pepper grass, but appeared 

 to attack also, by preference, turnip, horseradish and cauliflower."* 



Control. This fact of the preference of the beetles for the wild 

 food-plants might be utilized by using them as a trap-crop, planting 

 them, if necessary, as advised for the harlequin cabbage-bug 

 (page 371), and then removing and destroying them as soon as the 

 beetles had oviposited, which would probably be about the middle 

 of May in the latitude of Washington, D. C. Although no prac- 

 tical experiments in its use seem to have been tried, a thorough 

 application of arsenate of lead at from 3 to 5 pounds to 50 gallons 

 would undoubtedly destroy many of the beetles when they are 

 feeding on the foliage in early spring and after they emerge in June. 



* Quotations from Chittenden, I.e. . 



