Flight and Attraction of Mosquitoes 99 



access to the interior of dwellings varied from 7000 

 to 22,000. It was necessary for office men to bum 

 smudges and wear leggins. The seats of cane- 

 seated chairs were covered with paper, and many 

 devices invented to make Hfe more pleasant. 

 During the worst part of the period of influx any- 

 one out of doors at dusk was bitten many times 

 per minute. 



It was evident that some new source oi Anopheles 

 had been brought into existence. Wherever anti- 

 malaria work had been done before, aU known 

 production areas were thoroughly examined, but 

 gave no clue to the new situation, as they were 

 in normal condition. The area under inspection 

 for propagation places was extended. Mosquitoes 

 were present in the daytime in all places sheltered 

 from the sun and wind, except at the east of the 

 settlement. To the south, was the shore of Gatun 

 Lake along which much plant growth, debris, and 

 floating islands collected. Certain aquatic plants 

 were growing in solid masses from the shore line out 

 into the water, and filled the spaces between the 

 floating islands that had collected near the shore. 

 Vines were growing on the debris, and the floating 

 mass was more or less continuous along the shore. 

 All of this new possible production area was care- 

 fully examined and very few larvae were found. 



