Comparative Observations on the Morphology and Biology of some Hymenopterous Parasites of Carrion-infesting Diptera

The biology and larval morphology of three Alysiine Braconids and one Chalcid, parasites of the pre-imaginal stages of some carrion-infesting Dipterous larvae, are described. 2. The mode of hibernation of the parasites is recorded. 3. The oviposition of Alysia manducator and Aphaereta minuta is discussed in detail, attention being drawn to the hitherto neglected sense-organs located in the tarsi of these two species and to their importance in the process of oviposition. 4. The differing responses of full-grown Lucilia sericata larvae to parasitism by Alysia manducator at high and low temperatures are suggested to be due to differences in the physiological states of the host larvae at these temperatures. 5. A comparative study of the three endoparasitic Alysiines suggests that Alysia manducator may have reached a state of endoparasitic life relatively later than the other species studied, or at least has not yet reached such an advanced stage of endoparasitic specialisation as have Aphaereta minuta and Aspilota nervosa. 6. The growth of the egg in Aphaereta minuta and Alysia manducator and of the larvae of Mormoniella vitripennis is discussed.