INSECTS INJURIOUS TO CABBAGE, ETC. 



317 



eration being sometimes noticed in late cabbage in early fall. 

 On Long Island, N. Y., the Iarva3 have been observed as abund- 

 ant upon cabbage stumps in September and October, working 

 above ground, and the adults and eggs have been common around 

 the adventitious buds. Rough estimates indicate 300 to 1500 

 maggots per acre on these stumps. The puparia of the last, and 

 in the North possibly some of those of the second generation 

 remain in the soil over winter, though there is some evidence that 

 the flies may also hibernate in the Middle States. 



Control. The most effective measures of control consists in cul- 

 tural methods and preventives, but little practical success having 

 attended the use of remedies to kill the maggots. 



Cultural Methods. Inasmuch as the puparia remain in the soil 

 or in the old roots or stumps over 

 winter, it is important for this as 

 well as other cabbage pests to 

 gather and destroy all the refuse 

 of the crop as soon as possible and 

 then plow infested land thorough- 

 ly in the fall. Mr. Schoene has ^^ 

 shown that by plowing badly in- ry 

 fested seed-beds six or seven ^ 

 inches deep that only one-fourth 

 as many flies emerged as where 

 the soil was undisturbed. A ro- 

 tation of the crop will be of value 

 where cabbages are not grown on 

 large acreages. Cabbage and 

 other cruciferous crops should not 

 be planted after each other, as all 

 are affected by the same pests. It is evident that if the crop is plant- 

 ed at some distance from that of the previous year, and as the flies 

 are known to avoid wind-swept fields, that many of them will not 

 succeed in finding the new planting. 



As the maggots infest wild mustard and various similar weeds, 

 these should be destroyed as far as possible and crops affected by 

 the maggots should not be planted on or near land badly infested 

 with such weeds if avoidable. Wild mustard may be readily killed 



-* *&&-* \- 

 FIG. 266. Eggs of cabbage maggot 

 at base of stalk. (Photo by 

 Headlee.) 



