EXPERIMENT STATION BULLETINS. 



253 



THE BARRED-WINGED ONION-MAGGOT. 



(Chcetopsis cenea WiedJ 



In October, 1899, two onions were sent to the writer from Climax, Mich. These onion - 

 appeared to be infested with the common onion-maggot. The serious results that have 

 since come from the species sent at that time induces us to give this preliminary notice 

 with the intention of carrying on experiments, and later of giving a more detailed and 

 full account, in the light of such future experiments. 



The onions aboTe mentioned contained a number of small white maggots about five- 

 sixteenths of an inch in length. Two or three of them were preserved in spirits and the 

 onions with the remainder of the larvae were placed in a suitable cage in hopes of rearing 

 the adults. In the spring the adults were obtained, besides several pupa; that did not 



Fig. 18. — Barred-winged Onion-maggot. Chatopsis wnea from Riley and Howard Insect Life. 



U. S. Department of Agriculture. 



succeed in transforming. These puparia were polished brown, about three-sixteenths 

 of an inch long. The flies that emerged measured about three-sixteenths of an inch in 

 length and with the wings laid back, about one-quarter inch from the front of the head 

 to the tips of the wings. In color, the fly is njetallic blue-green except the head, which 

 is mostly hoary, with brownish-black eyes. The wings are transversely banded with three 

 smoky bands, the outer two bands coalescing at each end. The fly was so different from 

 anything known to work on onions, that it was sent to Dr. Howard, of the Depart- 

 ment of Agriculture, through whose kindness it was identified as Chcetopsis <vnea by 

 Mr. Coquillet. 



Mr. Andress, from whom the original lot came, writes me that he composted 700 

 bushels of onions because of this insect, or what he supposed with good reason to be 

 this insect. At least the samples sent me were taken from the same lot of injured bulbs. 

 He wrote me later that his entire crop of 1900, amounting to 2,000 bushels, was 

 destroyed, and that he had stopped raising onions for a time. Other onion raisers in 

 that region have also had trouble with the pest. 



So far as the writer knows, this is the first time that onions have been attacked by 

 this insect, with the following possible exception: Prof. Slingerland, in his admirable 

 work on the cabbage maggot and the onion maggot, Bulletin 78, page 556, of the 

 Cornell University Experiment Station, says — "In his report for 1893, page 441, Prof. 

 J. B. Smith mentions that some experiments were made on a fly larva which was at 

 first mistaken for the onion maggot. He writes us that this Ortalid larva was 

 remarkably resistant to almost anything that I could use. except kerosene." It is 

 very possible that the trouble in New .Jersey was due to this same pest, which seems 

 not to have been identified at the time of the trouble. 



In our cages the maggots passed the winter inside the onions. 



