422 Phylum Arthropoda 



Cool Cabinet. An electric refrigerator equipped with a special regu- 

 lator has served well the purpose of a cool cabinet. In this are stored 

 eggs, surgical maggots, pre-pupae and pupae to retard their growth. 

 The temperature is maintained at approximately io° C. A temperature 

 much above this permits too rapid development of the fly stages, and 

 much below results in a mortality which is too high. 



Other Apparatus. Petri dishes, beakers, pipettes, forceps, and the 

 apparatus for the bacteriological work needed is already a part of the 

 equipment of the hospital laboratory. 



PRODUCING STOCK FLIES ON UNHEATED MEAT 



The common blowflies, Lucilia sericata and Phormia regina, have 

 been used largely in the maggot treatment. The former species has 

 been employed mostly in studies by the writer. 



Usually pupae for the beginning stock of flies may be procured from 

 another laboratory. If not, a stock may be produced rather easily dur- 

 ing the summer from flies caught outdoors. Flies may be taken by in- 

 verting a large test tube over each fly of the species desired while it is 

 feeding on meat. The tube is removed and quickly stoppered. The 

 females are placed each in a separate vial containing a bit of fresh beef 

 and plugged. By the following day usually one or more of ten flies will 

 have deposited eggs. Flies are then reared on unheated meat preferably 

 from each of two or more layings of eggs. After emerging they are 

 definitely identified and stocks of flies for surgical maggots are reared 

 from them on autoclaved food. 



Eggs are obtained by placing two slices of meat about i cm. apart in 

 one half of a petri dish and inserting it in cage with flies. After 2 or 3 

 hours the dish with meat and eggs is removed and covered to prevent 

 drying of the eggs. 



Either rearing pan (Fig. 75) with the openings covered with cheese- 

 cloth only may be used. The one with the single large opening is pre- 

 ferred. About 250 gm. of coarsely ground lung and 50 gm. of chopped 

 liver is placed within the inner container of the larval rearing pan. 

 About 700 eggs are placed on the meat and put into a rearing cabinet 

 having a forced draft to outdoors. The larvae, when full grown, migrate 

 to the shavings and pupate. The residue of larval food is burned or 

 emptied into the sewer. The pupae with the shavings are put in 

 shallow pans, inserted into empty fly cages (Fig. 74) and placed in the 

 fly cabinet (Fig. 78). If flies are not needed at once late pre-pupae 

 and early pupae may be stored in the cool cabinet at io° C. for 2 weeks 

 or more. If desired they may be shipped conveniently in a mailing 

 tube. 



