REPORT OF THE SOCIETY 43 



The method of establishinjr these plots is briefly as follows. A suitable location 

 is chosen and a rough line is run around a block of one or two acres. The trees 

 on this block are then consecutively numbered, either with white paint or by 

 means of aluminum tags, fastened to the trees with copper wire or copper or 

 brass nails. The paint method is probably much the better since it is consider- 

 ably cheaper and it has this advantage, that individual trees are very much 

 easier of subsequent location. 



Sample plots are proving of invaluable aid to forest insect problems. Without 

 exact records of individual trees continued over a number of years, it is prac- 

 tically impossible to obtain satisfactory data on certain phases of the work. 

 On the sample plots, however, where the numbering of the trees makes their 

 annual location easj% entomological investigations can be conducted wdth much 

 greater efficiency than is otherwise pcssible. The sample plot is not intended 

 as a direct control measure or anything of that sort, of course. Its value lies 

 entirely in the field of experimental investigation, and it offers a sure and effic- 

 ient method of learning ever,ything pcssible about the life history and habits 

 of the various insects upon which we have to make war. When we get all these 

 facts within our grasp, then, and only then, will we be able to arrive at methods 

 of control which wnll effectively check in their incipiency any aangerous forest 

 insect outbreaks of the future. 



EXPERIMENTS ON THE CONTROL OF THE ONION MAGGOT, 1921 

 By W. Lochhead and W. J. Tawse, Macdonald College 



In collaboration with the Dominion Entomological Branch, the Entomol- 

 ogical and Horticultural Departments of Macdonald College carried out exper- 

 iments in the spring of 1921 against the onion maggot. For several years this 

 insect had caused severe losses to the onion crop in the truck gardens in and 

 about Montreal, and the owners gladly placed their fields at the disposal of 

 these Departments for testing out any method which gave promise of relief. 



The experiments w^ere conducted on six farms, viz., in Rcsemount on the 

 farms of J. and M. McEvoy, in Outremont on the farm of Paul Wattiez, in Cote 

 des Neiges on the farms of A. Savoie and A. Deguire, and at Macdonald College. 



The Arsenic Bait. — The method of control selected was the application of 

 poisoned bait of sodium arsenite and molasses, prepared as follows : — 3^oz. sodium 

 arsenite was dissolved in one gallon of boiling water, and 1 pint of cheap molas- 

 ses added. This bait was applied in two ways:— (1) in shallow pans, placed 

 at regular intervals throughout the field, and (2) as a spray. 



The pans used were round shallow tins, about 13/2 inches deep and 6 inches 

 wide, costing 7 14^ each. 



Into each pan a small lot of excelsior was placed and the sodium arsenite 

 mixture poured upon it, with the idea that the flies would the more readily get 

 access to the mixture. About 20 pans w-ere used per acre, and they were re- 

 filled every week for four weeks. 



