1. Pure-line breeding of Calliphora erythrocephala is difficult owing to the fact that gravïd females will oviposit at a distance from decomposing meat and the newly hatched larvae will crawl long distances and pass through minute openings to reach the food.

2. A simple and convenient cage for breeding blow-flies is described.

3. To obtain eggs free from contamination meat is plunged in boiling water before being put in the cages; and the vessel in which it is placed is sup ported on a glass cylinder standing in a dish of water.

4. The larvae are fed on horse-meat placed upon sawdust in a large watch-glass resting upon sawdust in a bowl. The bowl rests upon a support surrounded by water.

5. Pupation occurs in the sawdust beneath the watch-glass and puparia are separated from the sawdust by sieving.

6. Pupae are kept in glass dishes with closely fitting covers to prevent parasitism by Hymenoptera.

7. At a temperature of 21° C. the complete life cycle takes about 1 month.