106 
Psyche 
[June 
the C. cassius described from the Congo. If the hypothesis 
which I advanced in my paper of 1928 be accepted, the latter 
specimen may be supposed to have been infected by Mermis 
as an adult worker minor larva just before spinning its co- 
coon, whereas the minutior mermithergate was infected as 
a queen larva which had developed slightly beyond the stage 
at which, by some difference in feeding, it might have been 
converted into a normal worker major. 
DIPTERA DESTROYING SNAILS 
In a series of papers entitled “Natural History Notes 
from North Carolina” (Journ. Cincinnati Soc. Nat. Hist., 
vol. 17, p. 72, 1894), A. G. Wetherby under Zonites elliotti 
Redf. says : “This shell is destroyed by a parasitic larva, the 
imago of which is a small and active species of Diptera. The 
grown larva occupies the shell as a pupa house after devour- 
ing the inmate. I have noticed this habit of the Diptera in 
the case of but one other species, and that is Polygyra fas- 
tigans Say. At the only locality where I have collected this 
latter species, more than half the snails were affected, and 
the number of dead shells holding the empty pupa cases, 
were sufficient testimony to the activity of the parasite.” 
It would be interesting to know what this fly really is. 
A small Sarcophagid — Helicobia helicis Town, was bred 
from a snail — Polygyra thyroidus Say. I have always looked 
up this record as only accidental, for the fly is common and 
has been bred from a number of species of insects, and in 
many cases is considered a true parasite (Aldrich, “Sarco- 
phaga and Allies in North America, pp. 158-161, 1916). Dr. 
J. Bequaert however, has described a Sarcophagid repre- 
senting a new genus and species — Malacophagula neotropica 
from a snail — Bulimulus tenuissimus at Para, Brazil, which 
he considers a true parasite of the snail (Journ. Parasito- 
logy, vol. XI, pp. 201-212, 1925). 
C. W. Johnson. 
