550 



NEW JERSEY AGRICULTURAL COLLEGE 



throiiglioiit the growing; period. These irrefrularities of appear- 

 ance liavc interfered somewhat with our judgment concerning- the 

 vahie of ]irevent.ive application, bw,anse in some cases at least it 

 was an o]K'in question ^vhether exemption from attack was due to 

 the ap])licatioii or to some natural cause tluU would have produced 

 the same effect had no a])plicati(>n whatever been made. 



])espite these ditHculties it was decided to attempt a series of 

 tield experiments on cabbage and onion maggots during the season 

 of 1906, and to secure the co-operation of a few practical growers,, 

 materials to be furnished by the office, growers to make the appli- 

 cations, results to be judged by both parties. 



Briefly stated the life cycle of the common r(Kit maggots is as fol- 

 lows : The adult flies live throuii'hout the winter in such shelter as- 



Fig. 13. 



End segments of the Onion Maggot (1) and of the Cabbage Maggot (2) ; much enhirged. 



Original. 



they can find about the fann. They appear in spring about the 

 time their food plants are well started, lay their eggs on the plant 

 as near to the surface of the soil as possible, and when these hatch, 

 within a day or two, the young maggots begin to dig their way 

 into the root, stem or bulb, as tlie case may be. Injury does not 

 usually become noticeable until the maggots are so well advanced 

 in growth, or so protected by being imbedded in plant tissue, that 

 remedial measures are apt to be too late to kill the insects or to save 

 the plajits. When full grown the maggots usually move a little 

 distance from the plant, contract and form pupal cases, and lie 

 quietly a few days before the final change to the adult fly. There 

 may be several destructive broods in the course of the season, or 



