156 Psyche [August 
occurred again. The resultant progeny proved to be two females 
from two of the puparia, emerging on the 19th of October. 
b. Experiment similar to a. The following day three pairs of 
the parasite from the same source as in preceding were confined with 
17 of the same host puparia, the resulting progeny proving to be 
one male and one female, emerging on October 19 following. 
The experiments indicate fecundity, give the approximate dura- 
tion of the life cycle and establish parthenogenesis, which, however, 
remains to be verified. They also show the readiness with which 
the puparia of Phormia are attacked in confinement. 
HaBits aND BrioLoGgy IN GENERAL. 
As the observations on all points of the life history and biology 
of this parasite were necessarily desultory, they can be presented in 
no other way than one seemingly fragmentary. For convenience 
and brevity they are summarized or collected under the following 
headings. 
A. Nature of Parasitism. In the 309 (77 °@’s, 181 °’s, 51 unde- 
termined sex) cases of parasitism which were isolated in small gela- 
tine capsules with special reference to the nature of parasitism, of 
which all but nine of the hosts (4 °’s, 5 °’s of the parasites) were 
Musca domestica, every one yielded but a single parasite, which 
shows beyond doubt that the species is solitary in habit, even when 

— rarely — attacking comparatively large hosts such as Chrysomyia 
and Phormia are. In a critical examination of the hosts, after the 
emergence of the parasite, it was found that in nearly all cases they 
were considerably reduced in bulk, but not noticeably in length, 
recognizable as pupe, flattened, along the abdomen especially, hard- 
ened, shrunken and blackened — not collapsed or eaten away — 
indicating that the larval parasite was attached to the external 
body-wall of the host, obtaining its nourishment by absorption 
through it. This indication has been proven to be a fact by several 
direct observations made on dissected hosts, known to be parasitized 
by this species, and the further fact established, namely, that the 
larval parasite has no particular choice as regards the portion of the 
body of the host to which it attaches itself or rather to which it 
becomes attached. The destruction of the host is more complete 
than with Nasonia, for some host pupe are mere hollowed-out 
