G. S. Graham-Smith 
533 
males never left the puparia in which they developed. Some of 
the holes seemed too small to allow the males to escape. Froggatt’s 
observations, to be quoted later (p. 537), in regard to the relations 
of the sexes in another chalcid, N. brevicornis, are of some interest 
in this connection. Very rarely living chalcid larvae were found in 
puparia with pin-holes. The intact puparia nearly all contained the 
hard dry mass mentioned above and living chalcid larvae (Plate XXX, 
figs. 13, 15, 16), the numbers present in the large puparia varying 
from 17 to 41, with a mean of 27, and in the smaller puparia from 8 to 25 
with a mean of 16 1 . Very infrequently in such puparia dead adult 
chalcids were found together with living larvae. Every puparium 
attacked by the chalcid was found to be lined by the thick membrane, 
characteristic of a puparium containing a braconid larva. The chalcid 
was therefore in all cases a hyper-parasite. Further evidence that this 
was the case was afforded by dissecting the hard, dry mass mentioned 
above, which invariably contained a small, black, rod-like object, 
probably an accumulation of excrement, always present also in dissec¬ 
tions of healthy braconid larvae. Whether this chalcid is usually a 
hvper-parasite or not is uncertain, for it had little or no opportunity 
of infecting healthy fly pupae, since the flies had emerged or were just 
about to emerge before the chalcid commenced its attack on the pupae. 
The early batch of braconids were also emerging at this time and probably 
escaped, but the chalcid seems to have parasitised almost every remaining 
pupa containing a living larva. It is capable therefore of causing an 
immense amount of destruction. If it is usually a hyper-parasite on the 
braconid larvae it is not an insect to be encouraged since it kills off large 
numbers of parasites very destructive to flies; if on the other hand it 
usually attacks fly pupae during the summer months it is most beneficial, 
its powers of destruction being so very great; if lastly both braconid 
and fly larvae are commonly parasitised, its beneficial action is somewhat 
neutralised. (See also p. 543.) 
A fly pupa buried in the ground lies in a cavity considerably 
larger than itself and it seems possible that in most cases this cavity 
is connected with the surface by minute passages sufficiently large 
to admit chalcids. It may be of interest to mention that a pupa, 
found just below the surface of the ground on March 18, 1916, contained 
a number of chalcid larvae, but showed no evidence of previous parasitism 
1 Some puparia containing chalcid larvae have been kept under observation at different 
temperatures since November, 1915. The results obtained up to June 2, 1916 are 
recorded on p. 543. 
