Flies belonging to the genus Pseudochaeta are widely distributed in the United States and southern Canada but the allied genus Phaenopsis has not been recorded hitherto from North America. A recent study of the accumulated material in these genera has brought to light a number of distinct species, which are described below. I am especially indebted to C. F. W. Muesebeck, Dr. R. H. Beamer and A. R. Brooks for the loan of material. Types of the new species are in my collection.

This paper describes all stages of the spruce budworm parasite Apanteles fumiferanae Viereck, including the adult. Illustrations of all stages are presented. A short account of the life history of the host is included.