342 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



The present data suggest that the species is sporadic in its attacks 

 upon corn. There are but three recorded outbreaks in the state of 

 New Jersey for the period from 1885 to 1914, although New Jersey 

 was one of the first states in which its presence on corn was noted. It 

 may be that the corn-feeding habit is onl}'- occasional and that the 

 larvae normally lead a predaceous existence well hidden among close- 

 growing vegetation. 



LIFE HISTORY, NATURAL ENEMIES AND THE POISONED BAIT 

 SPRAY AS A METHOD OF CONTROL OF THE IMPORTED 

 ONION FLY (PHORBIA CEPETORUM MEADE) WITH 

 NOTES ON OTHER ONION PESTS i 



By Henry H. P. Severin, Ph.D., Wisconsin Agricultural Experiment Station, and 

 Harry C. Severin, M.A., South Dakota State College of Agriculture and Mechanic 

 Arts 



I Introduction 



As onion growers in some parts of Wisconsin have been forced to give 

 up the business of growing onions on account of the ravages of the 

 imported onion fly (Phorhia cepetorum Meade), an investigation was 

 started to determine the life history, natural enemies, probable causes 

 of the enormous increase of the pest and the value of the poisoned bait 

 spray as a method of control. In this paper a few observations on 

 other onion pests will also be noted. A more detailed paper on the 

 imported onion fly and other insects injurious to onions "^dll appear in 

 the Wisconsin Academy of Sciences, Arts and Letters. 



II Life History 



In the process of oviposition the imported onion fly usualh^ endeavors 

 to force its ovipositor between the onion stem and the ground, but 

 when the earth is tightly crusted against the plant, the egg-laying 

 organ is unable to penetrate the hardened soil. The female fly ma}^ 

 then oviposit'in a crevice near the onion stem, or if a small crack is not 

 available, the pest vAW sometimes crawl in holes or under lumps of dirt 

 an inch or two from the onion plant to deposit its eggs. 



The eggs are usually deposited from one-eighth to one-fourth of an 

 inch below the substratum, and are glued to either the soil or stem. 

 Sometimes the eggs may be found above the surface of the ground 

 attached to the stem, T\dthin the axil of a leaf or to the leaves them- 

 selves. The number of eggs which are laid at one deposition ma}' vary 

 from one to fifteen. 



^ Permission has been granted by Dii-ector H. L. Russell of the Wisconsin Agri- 

 cultural Experiment Station for the advanced publication of this paper. 



