METHODS FOR THE STUDY OF BLOWFLY POPULATIONS II. THE USE OF LABORATORY-BRED MATERIAL

The advantages and disadvantages of laboratory-bred material for fly-marking experiments are discussed. Experimental evidence suggests that the tendency to uniformity of history of laboratory-bred blowflies in relation to protein-feeding produces no rhythm, apparent in the first 4 days at least, in their response to protein bait attractants. The change from insectary environment to field conditions may sometimes result in either a greater or a lower proportionate recapture of a laboratory-bred sample than that for a comparable wild-caught sample. The nature of the difference is apparently associated with the weather conditions of the release area, but may be due to other causes, probably including physiological debilitation of laboratory maintained strains.