EXPERIMENT STATION REPORTS. 219 



KEFORT OF THE SECTION OF ENTOMOLOGY. 



To the Director: 



Sir: — ^The present fiscal year lias witnessed no clianges in the per- 

 sonnel of the section of entoniolojiy. However, at the end of this tiscal 

 year, June .30, Dr. W. L. Chandler will be transferred to the Department 

 of Bacteriology. The projects in parasitology will henceforward be 

 carried on by the Department of Bacteriology and microbology in the 

 Veterinary Division. 



THE GREEN PEA APHIS. 



IlUnoia Pi si 



The summer of 1922 was notable for the prevalence of the pea aphis 

 {JUinoia pisi). On June lo, 1922, a trip was made in company with Mr. 

 Harman, Extension Specialist in this department, to Kent City to view 

 the fields of canning peas with Mr. J. Hackley Skinner, Agriculturist for 

 the Roach Canning Company, and Dr. Chas. Woodbury, National Can- 

 ner's Association. The fields were very badly infested and several tests 

 of dusts were made with a large power duster. However, it seemed a 

 question whether the dusting paid in this case since the vigor of the 

 peas had already sunk so low that the increased yield was hardly ex- 

 pected to pay for the application. The figures show the appearance of 

 louse infested plants and also a healthy pod compared with one injured 

 by lice. At the time of harvest the effect of the infestation was clearly 

 demonstrated. 



On November 9th and lOtli a conference of entomologists and others 

 interested in the business of pea culture was held at Chicago where the 

 whole question was discussed and experiences exchanged, after which 

 a plan for co-operation was outlined. Representatives from California, 

 Alabama, Wisconsin, Minnesota, Michigan, Indiana, Illinois, Maryland, 

 New York and Ohio being present at this meeting, the following fact 

 seems to have been demonstrated viz. — "that the cost per acre of large 

 spraying operations is from ?f3.50 to -if 6.00 per application, including 

 cost of material, labor and depreciation of machinery, and aphis control 

 will require, under ordinary conditions at least two applications. The 

 expense of dusting, based on present data and costs of materials, is 

 slightly higher than that of spraying. The speed with which dusting 

 may be done, however, is much greater, and this counts in cases of 

 emergency. 



On May 9, 1923, the Insect Pest Survey of the Bureau of Entomology, 

 reported in special report number 25, the presence of the pea-ai)his seri- 

 ously injuring alfalfa from Kansas City to Boonville, Missouri. This 

 report was turned in by Professor Haseman of Missouri. 



On the receipt of this report the writer computed, by means of the 

 number of isophanes intervening between Kansas City, Missouri and 



