February, ’23] 
BRITTAIN: CABBAGE MAGGOT CONTROL 
65 
The method employed was as follows:— 
Twelve young cabbage plants were set out and covered with screens 
at the time of planting and around each was placed 50 newly deposited 
eggs. On the ninth day thereafter two plants were treated in the usual 
manner with corrosive sublimate (1-1,000) or creosote dust 1%, and 
two more each day for the following five days, when all had received 
treatment. 
In each case an equal number of checks were left untreated. In 
this series the exact age of the maggots was, of course, unknown. The 
incubation period for the eggs of this insect may be from 3-13 days, 
the average varying from about five to eight days in different seasons. 
Most of the treated plants, therefore, would be infested with very young 
larvae. 
The work was accordingly duplicated with maggots reared in the 
laboratory, the definite age of which was, therefore, known. Maggots 
of from 5 to 11 days old were employed. 
The results of this series of tests is shown in the accompanying table. 
It will be seen that in the case of the first series, no maggots managed 
to survive in any case with the corrosive sublimate, though a varying 
number were found on the untreated plants. The fact that better re¬ 
sults were obtained than last year is doubtless owing to the better pene- * 
tration of the material due to a moister soil. The results from the creo¬ 
sote are only slightly less satisfactory. 
Effect of Corrosive Sublimate and Creosote on C. M. 
SjMaggots Reared in Field 
Application No. on treated plant No. Remarks 
Corrosive on 
Sublimate Creosote Check 
9 days after deposition.0 
10 “ “ “ . 0 
11 “ “ “ . 0 
12 44 44 “ . 0 
13 14 44 4 4 .0 
14 4 4 4 4 4 4 0 
5 day old maggots 
0 44 44 44 
Y «< 44 44 
g 44 44 44 
Q 44 44 44 
10 44 44 
S 2 Maggots Reared 
.0 
.0 
.0 
.1 
.0 
.2 
The figure given for the checks is the 
0 5 
0 12 
0 24 Tunnelling noticeable in 
stems with both materials. 
1 19 Tunnelling noticeable in 
stems with both materials 
1 19 Tunnelling more exten¬ 
sive showing where insects 
had been at work. 
2 14 Tunnelling more exten¬ 
sive showing where insects 
had been at work. 
in Laboratory 
0 7 
0 4 
1 6 
1 10 
4 8 
2 14 
average of two distinct lots. 
