DEVELOPMENT OF CYNIPID HYPERPARASITES 455 
OVIPOSITION. 
The female Charips oviposits in the Aphidius larva 
only while the aphid is alive. In this it differs from other 
hyperparasites, such as Lygocerus (Proctotrypidae) and 
Asaphes (Chalcidae), which insert their eggs only after the 
host has woven its cocoon. My observations in this respect 
are opposed to those of Gatenby (8), who says: * The Cynipid 
parasitic forms associated with aphids apparently never attack 
live Aphidae, but seek out the dried skins of those already 
parasitized by an Aphidius.’ 
Subject to the condition that the Braconid larva shall still 
be bathed in the body fluids of its aphid host, the Cynipid 
has considerable latitude in its choice of a victim. The 
Aphidius usually selected is in the third or early fourth 
instar, but a second instar larva may be chosen (Text-fig. 3), 
though in such eases there is no evidence to show whether the 
hyperparasite can complete its development. The number of 
eggs laid by one female appeared to be about thirty. Only 
one egg is inserted at each oviposition, and others, when 
found, are probably the result of subsequent attacks. 
The female Cynipid runs over the plant in an excited manner, 
vibrating her wings and tapping the aphides with her antennae. 
Healthy specimens are ignored, but the Charips seems 
to detect the presence of the primary parasite unerringly. 
When she finds an aphid containing a suitable host, she leaps 
on to its back, facing the head, and clings there firmly, despite 
its struggles, like a rider controlling a restless horse. Sometimes 
she is thrown off, but returns repeatedly to the attack until 
the aphid is exhausted into passivity. The actual insertion of 
the ovipositor takes from two to six minutes. This leisurely 
procedure is not surprising when it is remembered that. the 
cuticle and body-wall of the aphid must be pierced before the 
probing for the host can begin, and as the Aphidius larva 
lies among the mass of aphid embryos its location can be no 
easy matter. Hven when found the mesenteron is so distended 
with food that the body cavity is correspondingly reduced ; 
