On June 8, 1910, in the woods near Brookline, Massachusetts, W. F. Fiske, then in charge of the Gipsy Moth Parasite Laboratory, collected an adult of the rare beetle Chromatia amoena Say (determination by the late Dr. E. A. Schwarz). Having no killing bottle, he placed the specimen in a match box. On the following day he found that the larva of a Dipternus parasite had issued and pupated in the box. The adult failed to emerge and the puparium was unfortunately discarded. In an attempt to determine something of the life history of the parasite, I dissected the dead host and found in it the first and second stage mouth hooks and the second stage posterior spiracles which were of such unusual structure that they seemed worth while describing. A short paper on the parasite was therefore published in 1913l in the journal published by Professor F. Silvestri, in whose laboratory I was then working.