Tinted print exists at Pinewood - has been transferred to digibeta in black and white.
Various tints throughout - orange titles, images pink, tangerine, yellow. Produced by British Instructional Films Ltd. Edited by Professor Maxwell Lefroy, Imperial College of Science, London.
Inter-titles about how flies have been a plague unto mankind since time began... "Only one stage of the fly's existence is passed in the light of day. It has remained for the cinematography to reveal the phases passed in secrecy and darkness." Shot of a fly in extreme C/U. Fly lays its eggs on a refuse heap. Highly magnified eggs. Refuse heap. Maggots hatch out. There is a hook at the end of the maggot which they use to pull themselves around and to tear at food. The maggots burrow into the manure. The maggot turns into a chrysalid or chrysalis. The chrysalid turns darker and harder. C/U of three chrysalides. Flies crawl out of the chrysalides. C/U of fly emerging and flying away. Flies work their way upwards through soil. C/U of fly moving through powder. Fly bursts through surface and then rests for a while. The head shrinks and the wings begin to develop. A fully grown fly. Very short shot of fly feeding on a piece of food.
Note: this film is listed on the Secrets of Nature filmography although this seems to be a different version. There was probably another version with a Secrets of Nature title for distribution in schools.