INTRODUCTION 27 
General collecting. General collecting with a hand net is often 
rather nonproductive unless one has a previous knowledge of 
some of the habits of blowflies. Since many of the species are 
earrion-breeding forms any type of earrion should yield speci- 
mens, particularly when decomposition is not too far advanced. 
Fresh excrement of carnivores, soured but not rotten fruit, and 
melons during certain stages of decay are often favorable attra- 
hents. Many ecalliphorids may be collected upon foliage in sun- 
light with a hand net, particularly between the hours of 8:00 
and 11:00 in the morning. After that time, during the heat of 
the day, adult flies are too active to be caught in numbers by 
this method. Male specimens seem to predominate in collections 
made upon foliage, where they appear to congregate while 
feeding upon honeydew or seeking moisture. Parasitic species 
are not often collected in a hand net unless a breeding area is 
located. Species of Apaulina, for instance, may be abundant 
during the height of their breeding season where bank or cliff 
swallows are nesting. Callitroga americana may be collected 
about the wounds of warm-blooded animals. 
Trapping. Methods of trapping carrion-breeding blowflies 
have occupied much time, thought, and effort in this country, in 
southern Africa, and in Australia. Traps have been used not 
only in determining the status of certain species in various local- 
ities but also in the control of economic forms. Traps large 
enough to hold entire careasses dragged into them by horses 
have been designed for the control of one species; some have 
conerete bases. Other traps employ a wind-power apparatus 
which continually stirs baits composed of carcasses and water. 
Such traps catch enormous numbers of blowflies which are at- 
tracted to carrion. One small wire screen trap, such as indicated 
in figure I, will usually supply more specimens of the common 
blowfly species than may be desired for taxonomic purposes and, 
if used: at intervals over a period of a year or two, will yield al- 
most all the carrion-breeding species of the locality. Such a trap 
may be constructed according to plans given by Bishopp (1916), 
or may be purchased. Beef or hog liver, or the carcass of some 
available small animal, is the usual bait placed in the open con- 
- tainer below the funnel of the trap. Water sufficient to cover the 
meat is then added. Slight alterations in the bait will attract 
a different series of blowflies. For example, freshly exposed 
carrion attracts species of Phaenicia predominantly. Baits sev- 
eral days old attract species of Callitroga, and baits still a few 
days older, Calliphora and Cynomyopsis during the periods of 
the year when species of these two genera are abundant.  Sar- 
