The observations here recorded were made during the rearing of Alysia manducator, Panz., as a parasite for Australasian sheep-maggots by the Imperial Bureau of Entomology, and are published by permission of the Director, Dr. G. A. K. Marshall. They form merely a supplement to the accounts of this species included in two excellent papers by G. S. Graham-Smith (1916, 1919), and one equally thorough by G. M. Altson (1920).

The present studies were carried out in North Essex during August-November, 1926. I am very much indebted to Mr. B. Golding and Miss Golding, for giving me all possible facilities for working at Street Farm, Ashen ; and to my wife for keeping the time during the heart-beat observations.

Alysia manducator is a blackish, rather stoutly-built Braconid about a quarter of an inch in length. The female lays usually one egg in a Muscid maggot of considerable size. Very little further development appears to take place until the maggot pupates, when the Alysia larva rapidly consumes it and accomplishes its own metamorphosis within a silken cocoon with which it lines the puparium. The adult Braconid emerges a few weeks later at the anterior end of the puparium ; but eggs deposited in autumn do not complete their cycle until the following year, when about a third of the imagines appear in spring and two-thirds in the following autumn (Graham-Smith). No hyperparasites are known, but Graham-Smith has recorded destructive superparasitism by Melittobia acasta, Walk. (1916, pp. 533–535), and by Mormoniella (Nasonia) brevicornis, Ashm. (1919, p. 378). Altson (1920) has shown that buried puparia are normally beyond the reach of Mormoniella, which is not adapted for burrowing.