86 The Control of Mosquitoes 



screens on the leeward side of houses in large num- 

 bers while absent from screens on the windward 

 side. At Gatun, when the mosquito influx was at 

 its maximum, they were found at rest in brush and 

 under dead grass on the wind-swept hillside, in 

 large numbers under houses, and in any place that 

 afforded protection from sun and wind. This 

 condition existed for several months during the 

 dry season. No natural flight in the sunlight has 

 yet been observed. While no suitable hiding 

 places except vacant houses were without mos- 

 quitoes in the daytime, yet beyond the settled 

 area none were found. They only rested in places 

 between the brackish body of water and the vil- 

 lage limits; and when grass in which they were 

 resting was disturbed in the full sunlight they flew 

 about ten feet to the next nearest shaded place. 

 Large numbers were collected under houses 

 where the breeze was sufficiently strong to make 

 the lighting of a match difficult. These inhabited 

 houses were on posts from two to ten feet above 

 ground. The dry weather ground-cracks under 

 the houses were several inches deep and the mos- 

 quitoes collected in them, but when small bunches 

 of grass or dry hay were placed under the houses 

 they hid in these in preference to the cracks. 

 None rested on the floor beams under the houses, 



