THE KEPORT OF THE 



No. 36 



satisfactory aud t^afe results. \\"\i]\ cabbages growing in the same field under same 

 conditions as the caulillowers the loss due to maggot attack varied in different 

 parts of a two-acre field from 18 per cent, to 50 per cent. Where cabbages had 

 tar-paper discs applied as was tlie case in one acre, the loss averaged rather less 

 than 5 per cent, from maggot attack. This loss from maggot attack, when tar- 

 paper discs were used in previous years, is considered bv growers in the localit^r 

 a fair average annual loss. Where corrosive sublimate was used on cabbages the 

 loss bv maggot attack was less than 5 per cent, and the growth of the plant while 

 .-•omewhat better at the commencement of the year, was not appreciably different 

 at tlie time of marketing tlie crop. The summarized results are given herewith: 



TABLE I. — Cauliflowers — Averages axd Sujimary. 



Form of Treatment. 



Pe'ceulage. 



Tar paper discs 



Corrosive sublimat« — 



1 application. 1-- 6... 



1- 8.. 

 ]-10.. 



2 applications. 1- 6. . 



1- 8 . . 

 1-10... 

 8 applicatioos. 1- 6. . , 

 1- 8... 

 1-10... 

 No control 



Affected by 

 maggots. 



25.3 



f>8.tt 

 62.0 

 K4.0 



n.o 



62.0 



64.0 



1.8 



i'.s 



76.5 



Atfeclcd hy 

 other cau.ses, 



36.4 



3.9 



8.0 



16.0 



4.0 



8.0 



16.0 



19.2 



23.4 



19.0 



21.9 



LlFE-HlSTOEV JSTOTES. 



Iiiii-iuuch as all pi'ox ious study given the Cabbage Root Maggot in British 

 Coliunliia lias taken place in the Lower Eraser A'alley. this year's work in the 

 Ai'msti'ong district adds another localit}^ where this insect has been under obser- 

 \ation. The transplanting of the cabbages and cauliflowers was completed by 

 May ord in 191J). The first aulult flies were captured on May 7th in the field, 

 and on examination of 100 plants on this day, only 3 eggs were taken. Oviposition 

 was heavy previous to May 23rd and on this date small larvaB were found in the 

 root systems of some plants that were showing signs of injurj-. Two large half- 

 grown maggots were seen on this day also. Twenty-five plants were under more 

 or less continuous observation during the early spring and on the dates May 12th 

 and Kltli and June 4th, these plants carried respectively 59, 847 and 1,091 eggs, 

 the eggs on each examination being carefully removed by hand. It was exceed- 

 ingly interesting to note that the largest plants received the greatest number of 

 eggs and in view of the fact that the corrosive sublimate blocks contained the 

 largest plants the blocks were the greatest attraction areas. The same point is 

 drawn on page 27 of Bulletin Xo. 12 of the Dominion Entomological Branch, 

 1916, which details, so far as the l)ulletin relates to British Columbia, the life- 

 history studies carried on in the Lower Eraser Yalley. The sundry other points 

 in the life-histor}^ of this maggot in the Armstrong district are so closely allied 

 to the results detailed in Bulletin 12 on this insect that there is no neied to take up 

 further space in this paper for their discussion. 



