1910] Girault and Sanders — Chalcidoid Parasites Pil 
was reared quite incidentally, that is to say, without conscious effort 
on our part to augment it. From one experiment alone, there were 
obtained as many as seven thousand specimens, in round numbers, 
though we have no knowledge concerning the number which may 
have escaped. Further, the local abundance of this parasite is indi- 
cated by the fact that in at least a portion of the experiment just men- 
tioned, a portion selected at random, the percentage of parasitism was 
as high as 90 per cent. We have evidence to show, on the other hand, 
that this percentage of mortality of the host was by no means general 
but was considerably lower on the average for this season of the year. 
Thus, apparently this parasite had concentrated its attack at certain 
spots and while common over this locality was not exceedingly abun- 
dant over the whole, as the percentage of mortality given in the instance 
just mentioned would seem to indicate. 
It was the most abundant parasite present in our experiments and 
also the one which attacked the greatest numbers of different muscid 
hosts, the remaining chalcidoid parasites of importance mainly con- 
fining themselves to the house fly. 
K. Artificial Propagation. An unsuccessful attempt was made 
during the last week of September, 1908, to test the effect of the 
artificial propagation of this parasite on a badly infested garbage 
heap at the city dumping-grounds, Champaign, Illinois. The attempt 
was made too late in the season, however, and in addition, bad weather 
immediately following their liberation undoubtedly prevented activity 
on their part. 
On the afternoon of September 23, 1000 specimens of mixed sexes 
were scattered over the garbage heap, which at that time was a veritable 
breeding experiment on a large scale. Soon after their liberation, 
many of the parasites were noticed crawling over host puparia which 
had been formed about a half-inch below the surface of the soil along 
the edges of the garbage heap. Specimens other than those liberated 
were not noticed at the time, special search being made for them 
previous to liberation. 
On the date the experiment was inaugurated the percentage of 
parasitism by this species was very low as we know from the results 
obtained from a collection at random of 186 puparia; for by November 
6, 1908, 48 adult flies had emerged (of which 37 were Musca domestica), 
6 Spalangia and 2 Muscidifurax raptor Girault and Sanders MS. 
An examination made of the remaining 130 hosts, which were hibernat- 
