August, '17] TUCKER: PEGOMYIA FUSCICEPS AND FIELD CROPS 401 



for the enemy revealed it onlj^ in the pupal stage occurring in the soil at 

 short distances from the plants. The finding of the pest in this form 

 established the fact that the destructive stage, or maggot, had ceased 

 its ravages in this field. 



The work of maggots in seed potatoes could only be briefly inves- 

 tigated, but it certainly foreboded disaster to the planting that was 

 first inspected. Tubers that were dug up for examination consisted in 

 part or almost wholly of a rotten mass infested with the maggots. 

 Reduction of the parent stock in such manner meant that the sprouts 

 must soon die for lack of nutriment. In a field of more recent planting 

 where the tubers had just started to sprout, no defects came to view, 

 although the stock was found to be endangered by numbers of maggots 

 which reveled in the decomposing cotton seeds that had been put in the 

 rows for fertilization of the crop growth. 



Infestation of Cotton Seeds used for Fertilizer 



The discovery of the maggots existing among the rotting cotton seeds 

 buried under several inches of soil incited comment in regard to the 

 manner in which the infestation could have been initiated. The 

 introduction of these forms could not be explained in a way to satis- 

 factorily attribute sufficient ability on the part of the pest at any stage 

 to gain access into such a situation. The problem, however, admitted 

 of a simple solution which happened to be revealed through remarks 

 ventured by the grower. He pointed out the probability that the 

 cotton seeds had become infested with maggots previous to the time 

 when they were scattered in the field. According to his statement, 

 he used these seeds for fertilizer because in the first place they consti- 

 tuted a quantity which by exposure to rain had been rendered unfit for 

 planting or for sale. While being cast aside in such condition, the pile 

 of spoiled seeds had likely attracted parent flies which had then de- 

 posited their eggs in the damp decomposing mass, thus resulting in the 

 development of maggots under very favorable circumstances. 



Comments 



As adult flies cannot oviposit below the surface of the ground to 

 any depth, no maggot on hatching from an egg placed on the soil would 

 be able to penetrate far down unless guided by the stem of a plant. 

 By such means as the latter, the maggots can without doubt reach the 

 tubers of potato sprouts. 



In proposing an experiment for the benefit of a grower, he was asked 

 to place a few glass jars in an inverted position over some of Ijis 

 failing plants for the purpose of trapping a number of flies when they 

 should emerge from the enclosed soil after completing their develop- 



