1915] Behavior of Anopheles 261 
the south-west and therefore some irregularities occurred. In 
all cases the instrument was set about four feet from the ground. 
More mosquitos were caught during the evening flight. This is 
because the morning flight takes place higher in the air and 
the instrument was too low down to intercept it. 
Inasmuch as the glass planes are a barrier to the wind, 
it is worth while to consider the fact when deductions are 
being made. Our results, covering several years of records, 
show more mosquitos caught in traps on the leeward of buildings 
than to windward. Examining Quimby’s charts, a similar 
condition appears to exist. Cases “‘C”’ and “‘E”’ show more 
flies on the south side of the west plate. The mosquitos fléw at a 
quarter to the wind, i. e., in a south-easterly direction. There- 
fore more mosquitos should have been found on the west side 
of the south plate and the north side of the west plate. The 
actual catch shows more mosquitos on the lee side, and there- 
fore the breeding place should have been to the south-west and 
the mosquitos bound for the north-east, which of course was 
not so. 
A few tests were made using copper screen instead of glass, 
but the tanglefoot produced a coppery odor and verdigris, 
the results proving negative. A cloth screen, larger in area, 
would probably yield better results. One instrument is not 
enough; as they are inexpensive, several dozen should be placed 
about a suspected area, much on the order that mines are planted 
across the paths of ocean traffic. And not the least in importance 
human beings must keep away from these screens as long as the 
mosquitos are active. 
2. Mosquitos Harboring Under Buildings. 
Since the houses in Gatun are so well screened, and cracks 
in the floors and walls stopped up, mosquitos enter with much 
difficulty, the majority of them gaining entrance as doors 
are opened and closed. It was hardly thought possible that all 
the mosquitos that flew to Gatun one evening, returned the next 
morning. Therefore mosquito bar nets were spread under four 
buildings and a negro placed under each one, equipped with a 
chloroform-filled killing tube. His instructions were not to 
impede the entrance of mosquitos and to catch all that entered. 
