D. Keilin 181 
The larvae of S. filia are often parasitised by Hymenoptera belonging to the 
families of Braconidae and Cynipidae. 
3. Sarcophaga melanura Meigen. 
M. E. Seguy informs me that he has observed the females of this fly de¬ 
positing their larvae upon the slug Arion fuscus. In spite of the violent con¬ 
tractions of the slug and the abundant production of mucus the larvae make 
their way into the body of the host which is soon killed and liquefied. 
4. Engyzops pecchiolii Rond. 
A recent paper of W. R. Thompson (1921) contains much interesting in¬ 
formation concerning this fly. He dissected a female of E- peechiolii captured 
in the south of France (Gers) and found its internal genital organs well 
developed and the uterus filled with completely formed larvae ready to hatch 
from their eggs. The study of these first stage larvae revealed their close 
resemblance to the first stage larva of Melinda gentilis , which, as we have 
previously shown (1919, p. 442), lives as a parasite in Helicella virgata. The 
genus Engyzops was placed by previous authors among the sarcophagid flies, 
but according to Thompson the structure of the internal genital organs and 
the first stage larva show that this insect has more affinity with the Calli- 
phorine genus Melinda than with the Sarcophagids. 
The life history of E. pecchiolii is not yet known, but the resemblance of 
its first stage larva to that of Melinda suggests, according to Thompson, the 
possibility that in its early stages it also lives on snails. 
5. Lucilia dux and Pycnosoma. 
Under the title “Mortality among snails and appearance of Blue-bottle 
Flies,” we find in Nature (1919, civ. pp. 412-413) a very interesting letter by 
N. Annandale of the Indian Museum, Calcutta. The following are a few ex¬ 
tracts from this letter: 
“The residential parts of Calcutta are remarkably free, as a rule, from 
both house-flies ( Musca spp.) and blue-bottles. This is doubtless due to the 
excellence of the municipal sanitary arrangements, for at Sibpur, a few miles 
away, blue-bottles ( Pycnosoma or Lucilia dux) are not only extremely trouble¬ 
some in the houses, but are also probably connected with frequent epidemics 
of enteric, unknown in the better parts of Calcutta. For some years past I 
have been able to trace the flies to their breeding-ground. This has always 
been the dead bodies of the snail Achatina fulica, the largest land mollusc in 
Bengal_” “Fortunately it is largely a feeder on decaying vegetable and 
animal matter, and therefore does little harm to crops or gardens, and has 
even its value as a scavenger. Since, however, I found the maggots in the 
dead snails, I have noticed that the appearance of blue-bottles in this part of 
Calcutta invariably coincides with a heavy mortality in the mollusc, which 
appears to be subject occasionally to some kind of fatal epidemic and also 
