16 MISC. PUBLICATION 336, U. S. DEPT. OF AGRICULTURE 
Favorable daytime resting places for Anopheles are found under- 
neath buildings that are raised 2 or 3 feet from the ground and inside 
tightly boarded outbuildings or similar locations. In making the 
surveys a series of stations well distributed over the area under ob- 
servation are selected, and weekly, biweekly, or monthly collections 
are made (82, 92). At each location the most favorable resting place 
should be selected after examination of all the buildings on the 
premises. When the surveys are purely for comparative purposes, 
the collecting station does not always need to be an entire building, 
if it is found that one part is more favorable than another or that 
parts of the building are not conveniently accessible. Where the 
resting surface is fairly smooth and unobstructed, a well-trained and 
reliable collector, with the aid of a flashlight, can obtain satisfactory 
counts of the resting mosquitoes in much less time than would be re- 
quired for collecting the specimens in killing bottles. The sex can 
be determined and in most cases the species identified on sight. Col- 
lections over a definite period (10 or 15 minutes) have been used as 
an index of density, but they may be unreliable because of variations 
in the rate of collection under different conditions as well as in the 
mechanical limitations to the numbers of mosquitoes that can be 
collected in a given time. 
TRAP COLLECTIONS 
For most species the suction type of light trap (fig. 6) is very 
useful for obtaining samples of the mosquito population, for records 
of comparative abundance, and, in control areas, for immediate in- 
formation on the occurrence of outbreaks. In connection with con- 
trol work the traps are placed at strategic places throughout the area 
and are usually operated every night. For other purposes the traps 
may be run on a schedule of one or more nights each week. The 
traps should be hung in an open space with the hght itself 5 or 
6 feet from the ground, and they should not be placed in the immediate 
vicinity of a street hght. 
The number of mosquitoes caught per night frequently runs into 
the hundreds or even thousands, and many other kinds of insects 
are found in the killing bottles. Under these cenditions the task 
of separating and identifying the material is considerable, especially 
when the specimens are badly damaged cr wet. Species not taken 
while biting appear in the light-trap collections, and it has been 
found that the different bloodsucking species are not attracted to the 
lights equally. Over a series of nights the writers’ trap-collection 
records have shown more variation than the biting records, which, 
of course, are the more accurate index of annoyance. From a large 
series of trap collections made in Florida only an occasional specimen 
of Aedes aegypti has been obtained, and the numbers of Culex quin- 
quefasciatus and C’.. nigripalpus appear to be very small in compari- 
son with the amount of breeding in the neighborhood of the traps. 
This also seems to be true to some extent of Anopheles quadrimaculatus. 
The trap records, therefore, cannot be relied on as an index of density 
for these species. 
Boxes of various sizes and shapes, having the inside painted black or 
lined with black cloth, have been employed to attract mosquitoes, 
particularly anophelines and the house Culex, as a daytime resting 
