ON THE CHANGES IN CHEMICAL COMPOSITION ASSOCIATED WITH LARVAL DEVELOPMENT IN THE SHEEP BLOWFLY

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Abstract
SUMMARY: The most marked change in composition during embryonic development is the disappearance of fat typical of cleidoic eggs.The chorion probably consists of protein together with gome nitrogen‐poor constituent, perhaps a saturated fat or wax; chitin and other carbohydrates are absent, and ash and moisture contents are low.No great changes in composition occur during the first two larval instars, with the exception of a possible utilization of some reserve protein and carbohydrate while the larvae are establishing themselves on the meat.During the third and last instar, however, a considerable ieduction in moisture content occurs, and an extensive storage of fat takes place, beginning at about the stage at which previous work had shown a marked increase in resistance to starvation. There is also evidence for the accumulation of a large bulk of reserve protein and a smaller amount of reserve carbohydrate during this instar.The most important factor influencing the degree of uneaturation of the larval fat appears to be the nature of the food fat; iodine values show little variation with the state of development, and preliminary observations suggest that the influence of the environmental temperature is small.I wish to record my sincere thanks to Prof. P. A. Buxton for his active interest in this work, and to Dr V. B. Wigglesworth for helpful advice and valuable suggestions. I am also indebted to the Agricultural Research Council for the award of a Research Scholarship which has entirely financed this investigation.