328 APPLIED ENTOMOLOGY 



The number of generations in a season has been worked upon by 

 . several investigators with somewhat differing results. It seems probable, 

 however, that in the latitude of New York, the insect as a rule has three 

 generations though in favorable seasons four are possible, and in unfavor- 

 able ones only two may occur. Presumably, the number farther north 

 will usually be two, and farther south four may prove the usual number. 

 Weather conditions apparently have an influence on this hot, dry 

 weather hardening the roots of the food plants so that feeding is slower 

 than would otherwise be the case, and this same kind of weather also 

 seems to lengthen the pupa stage. It is interesting to note that the 

 insect though present in the Gulf States does not seem to be a serious pest 

 south of the latitude of southern Pennsylvania. It has been found as 

 far west as Colorado. 



FIG. 349. Cabbage Plant protected by a tar-paper disk around its stem. (Modified from 

 Britton, Fourteenth Rept. Ent. Conn. Agr. Exp. Sta. 1914.) 



Whatever the number of generations a season, the insect seems 

 able to reach the pupa stage before winter, and possibly become adult 

 in some cases. 



The Cabbage Maggot is most serious as a pest on cabbages and cauli- 

 flowers. It also attacks turnips, radishes, mustard and other cruciferous 

 plants, however, and late generations may live more on these plants 

 as the cabbage and cauliflower roots get older, tougher and less attractive 

 to the insects. 



Control. Cabbage and other plants, liable to attack while in seed- 

 beds, can be protected by covering these places with screens of cheese- 

 cloth. When the plants are set in the fields, tar-paper disks may be 



