22 THE BLOWFLIES oF NortH AMERICA 
gots may complete their growth and escape from the bait pans 
unless 1 teaspoonful of nicotine sulfate is added to each gallon 
of water used in the preparation of the bait. This will not reduce 
the attractiveness of the bait, and it will check the breeding of 
blowflies in the bait pan. A less odorous bait which will attract 
considerable numbers of blowflies is composed of one-fourth 
pound of dried whole egg stirred into 1 gallon of water. This 
bait will be more efficient if it is stirred frequently and kept 
alkaline by the weekly addition of 1 teaspoonful of sodium 
bicarbonate in each gallon of water. Milk, or casein and water, 
to which over-ripe bananas have been added makes a rather effec- 
tive attrahent for use about dwellings or stores. 
The container which holds the bait in fly traps is a very 
important factor. Small or deep containers do not allow the bait 
to produce the odors attractive to flies in sufficient strength and 
the resulting catches are proportionately small. The bait pan 
most suitable for use in the trap recommended is approximately 
4 inches deep and from 14 to 18 inches in diameter. It should 
be about 4 inches less in diameter than the diameter of the base of 
the cone. Such a bait container will hold a considerable quantity 
of bait and water and calls for relatively infrequent bait renewal 
during hot weather. Bait pans should be kept well filled and they 
should be washed at frequent intervals. 
Traps should be set upon platforms about 2 feet square and 
high enough to protect the bait from animals. The trap should 
be set where blowflies naturally congregate. During cool weather 
such flies will be found most frequently in sunny locations near 
buildings and protected from the wind. During hot, dry weather 
a better location may be in partly or wholly shaded places. A 
poorly situated trap will catch only a small part of the number 
that might have been caught in the same trap in a better location 
only a short distance away. 
Under ordinary circumstances traps should be emptied once 
each week. Dead flies piled high against the cone inside the trap 
will reduce the light which attracts the flies upward from the bait 
chamber, and the catching power of the trap will be materially 
redueed. To kill the flies in the trap before removing them. the 
antire trap may be given a residual treatment of DDT, the trap 
- may be placed in hot water, the flies may be killed with one of 
the numerous fly sprays, or they may be killed by dumping them: 
from the trap into an open fire. During summer months it is 
not necessary to kill flies that are caught, for the majority die 
very rapidly within the traps, especially when the traps have 
been treated with DDT. To empty a trap in hot weather, the 
