August, ’20] 
ZETEK: MOSQUITO CONTROL 
347 
powdered para-dichlorobenzene (2 grams); in another was placed 
powdered camphor (2 grams); the third was kept as a breeding cham¬ 
ber for A. calopus and received at frequent intervals larvae and pupae. 
Raisins and dates were used as food for the adults that emerged, though 
at times I would place my forearm against the screen and allow twenty- 
five fortunate mosquitoes to have a blood meal. Several hundred 
adults were always in this cage, and copulation in the air was a very 
frequent sight. The object of the experiment was to learn whether the 
mosquitoes will appear in the treated waters. The test was continued 
for one month. During this period no larvae were found in the treated 
waters. In the breeding jar, however, there were a large number of 
very young larvae, showing that oviposition was taking place. Enough 
water was added to all jars to make up for loss due to evaporation. It 
would appear that both camphor and para-dichlorobenzene act as 
repellents. 
(4) This experiment was made in Mr. Molino’s garden, and was 
carried out to learn the efficacy of the method under actual field condi¬ 
tions. The garden is divided into two parts, each with about the same 
number of ant-guards. All of these were emptied, scrubbed out well 
and allowed to dry for three hours. They were then filled with tap 
water. To ten of these was added powdered para-dichlorobenzene, 
two grams to each guard. To ten others, powdered camphor was 
added, two grams per guard. These twenty treated guards were well 
scattered among the others. Six days later the first inspection was 
made. No larvae were found in the treated guards. Nearly all of 
the controls had larvae. During this 6-day period we had twenty-six 
hours of fairly heavy rain. This test indicates that the method pro¬ 
posed is effective. 
The infested ant-guards were emptied, scrubbed out and filled with 
tap water. The twenty treated guards were left exactly as they were. 
Five days later an inspection was made; this was eleven days since 
the chemicals were first introduced. Three of the camphor treated 
guards and two of the para-dichlorobenzene ones had larvae. Six of 
the controls had larvae, much greater in quantity than in the infested 
treated guards. We had seven hours of rain during this 5-day period. 
This test shows that both camphor and para-dichlorobenzene are 
effective in inhibiting the development of calopus larvae, but due to the 
rains and the heat, it is necessary to add fresh chemicals once each week. 
But, even if ten days pass before fresh material is added, there is little 
danger because it is highly improbable that any larvae that may be 
present would reach the pupal state. 
(5) It was now thought that perhaps the chemicals could be used in 
lump form as well, and perhaps be effective: also, that perhaps the 
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