30 THE BLOWFLIES OF NortH AMERICA 
(1939), in experimenting with various media for the rearing of 
blowflies (particularly Phaenicia cuprina), found the following 
formula to produce full-grown larvae, under sterile conditions, 
in the same time as beef liver. 
Agar solution (one and one-half percent) ...... 93.0 
Yéast) (dried bakers’) svast. neste eee ee 6.7 
sodiumscehloride te. sae ee Pe 8 
The addition of fresh egg white instead of: agar solution pro- 
duced larvae in about 24 hours less time. 
A method of rearing larvae of Callitroga americana, an obliga- 
tory parasite on warm-blood animals, which have never been 
found to complete their growth normally on cold-blood animals, 
carcasses, or other nonliving media, has been developed by Melvin 
and Bushland (1936 and 1940). Their most recent formula for 
this medium is as follows: 
Water” .aausc aks 5 Sere er eee ame ol 1 liter 
Formalin (39 percent formaldehyde)......... 6 ce. 
Beef (finely ground muscle tissue) .......... Inks 
Blood, beef (citrated at the rate of 
3 gm. per liter) 
‘‘The ingredients are thoroughly mixed in the order given in 
a No. 2 galvanized tub approximately 15 inches in height by 2 
feet in diameter. The rearing tub is kept in a warm room (tem- 
perature range, 85 to 100 degrees F.). Newly hatched larvae are 
placed on the medium and begin to feed immediately. They are 
allowed to feed for three days and are then transferred to a tub 
of fresh medium where they feed for three or four days more 
before completing larval growth. During the first three days, ' 
several thousand larvae may be grown in one rearing tub but 
during the second three days, about 2,000 larvae will exhaust the 
food supply of a fresh tub.”’ 
These authors state that the formula given does not need to 
be followed strictly for satisfactory results but that the amount 
of formalin is important, for bacterial decomposition renders 
the medium unsuitable for larval development. The volume can 
be regulated according to the number of larvae being reared, 
it being important only that, regardless of the size of the con- 
tainer, the medium should fill it to the depth of approximately 
1 inch. 
Warmth, moisture, shelter, and aération are essential physical 
conditions for larval development of carrion-breeding species of 
ealliphorid flies, 
