134 BRITISH ICHNEUMONS. [ Sphecophaga 

soft, fleshy and white. The head is narrower than the anus, white and 
showing only somewhat indistinct traces of labrum and mandibles; it is 
blind and apodous, possessing only some transverse fleshy ridges on the 
back of the abdominal segments ; length of adult larva g—10 mm., with 
a central diameter of some 3 mm. 
Having demolished its host the larva constructs a very strong cocoon 
for itself at the bottom of the wasp-cell,* sufficiently stout to resist all 
attacks of the wasps to dislodge it, since the latters’ eggs are sometimes 
deposited upon this cocoon. The cocoon is oblong, hexagonal-cylindri- 
cal, rounded below, with the operculum flat or a little concave (André, 
xxxiv, 7), and often longitudinally wrinkled; within the cocoon has a 
beautifully delicate gold-coloured lining, in which the nymph is en- 
wrapped ; the length is about 6 mm. and diameter some 3 mm. The 

parasite emerges through a clean cut orifice in the centre of the oper- 
culum; the cocoons are said to have a strong smell like that of formic 
acid. It does not yet appear plain whether there be two distinct broods 
in the course of a year; if such be the case, some evidence exists that 
the brood emerging in the spring is fully winged, since it hatches out in 
the empty wasps’ nest, whereas that emerging later in the year is brachyp- 
terous, since there can be no need for it to vacate the then fully tenanted 
nest in order to propagate its race, and all the brachypterous examples I 
have seen were taken from the interior of the nests. But nothing is yet 
known respecting its oviposition. Undetermined Chalcididae have been 
* No other host is yet recorded but Bignell says, after considerable experience of this parasite , 
“ Sphecophaga is certainly not confined to the genus Vespa: it is quite impossible for a footless grub 
to leave the wasps’ nest to pupate somewhere else. It might turn out to be a parasite on Osmta rufa, 
and I have an idea that I removed the cocoon from an old wall infested with that bee" (tn lit. 3rd 
Dec., 1901). But it certainly pupates inside the wasps’ nest. He adds, more definitely (¢ lit. 23rd 
Feb., 1909), ‘‘It does not confine itself to wasps, as I have obtained its cocoon from a colony of 
Osmia rufa that had taken possession of the sunny side ef a house at Roborough, five miles from 
Plymouth, on 5th September, 1901." L. Semichon has recently published a ‘‘ Note biologique” on 
this species in Bul. Soc. Ent. France, 1908, p. 79. 
