INTRODUCTION 31 
The larvae mature in from 8 to 4 days in warm weather and 
then migrate from the food. They will enter the sand to pupate 
if it is not too moist or too dry. The food should be removed when 
all the larvae have left it, and the wire or cloth screen top may 
be placed on the cage when all the larvae have pupated. The 
sand in the cage should not be allowed to become dry; with a 
little experience one learns to judge the amount of water to 
be added daily. 
The pupal period varies with the species and also with the 
season of the year. Many of the species overwinter as mature 
larvae. In some instances a few days in an ice box and a gradual 
warming will hasten pupation. With favorable temperatures 
delayed pupation is usually the mesa he the sand’s being too 
dry or too moist. 
Certain calliphorid species cannot be reared in this way. Pol- 
lena rudis and species of Onesia which are parasitic upon earth- 
worms may be reared according to the technique of Keilin (1915) 
or Decoursey (1927). Sinee Apaulina larvae suck avian blood, 
the rearing of such species is a difficult procedure and each 
different species group may require different methods. 
Many of the species have never been reared and few facts are 
known concerning their biologies. The above procedure is satis- 
factory, however, for the majority of the species which have 
saprophagous habits in the larval stage. 
PRESERVATION OF SPECIMENS 
Emerging adults should be fed upon granulated sugar and 
banana for at least 24 hours before being killed and pinned. This 
procedure is necessary to fill out and harden the body wall and 
to allow sufficient time for the color to develop fully. The empty 
pupal ease should be placed upon the pin just below the adult 
specimen. 
In order to obtain specimens of the different instars, some 
larvae should be preserved upon hatching from the egg, others 
24 to 48 hours later, and still others when they start to migrate 
from the food source. Selected specimens should be killed by 
immersion in boiling water. I prefer to preserve muscoid larvae 
in a solution prepared according to the following formula: 
PEO US DCCC sys) i a tas oo ia tal d ‘suop sao 85 ee. 
PIAL aOR DELCO. (28 22s icccie pics wots scenusme 10 ee. 
SAR UY Pry ad OEE ERR ae ate aed SNL A Rain a D Ce. 
Specimens preserved in this solution retain their shape and 
color indefinitely and, after perforation with a fine needle, may 
