BIONOMICS AND DEVELOPMENT OF LYGOCERUS sp. 105 
PAIRING. 
No parthenogenetic ovipositions were observed, and about 
40 per cent. of the imagos reared were males. Pairing took 
place a few hours after emergence. It was noticed that the 
males paired only once. Thus Lygocerus differs from its 
Braconid host, in which a single male will fertilise two or three 
females successively. 
OVIPOSITION. 
The female Ly gocerus, when about to oviposit, runs in 
an agitated manner over the leaves infested with plant-lice. 
Living aphides, whether parasitised or not, are ignored, and 
I have never seen the Lygocerus make the mistake of 
ovipositing on an A phidius which had not begun to spin silk. 
The necessity is obvious, for until just before metamorphosis, 
the host is still bathed in the juices 6f:the aphis, in which the 
egg of the hyperparasite could hardly develop. Sometimes 
a pupa is chosen instead of a full-grown larva ; but these 
are never attacked in the later stages when the chitin is 
hardening. 
When a suitable host is found, the Ly gocerus runs round 
and over it with much excitement, tapping it repeatedly with 
her ‘antennae. ‘The act of oviposition usually takes from 
30-60 seconds. ‘The Proctotrypid stands either on the thorax 
of the aphis skin, facing the head, or on the leaf behind it with 
the tip of her abdomen against its posterior part. Hither 
way, the result is to bring the ovipositor, when exserted, into 
the curve formed by the body of the Aphidius as it hes, 
bent head to tail, in the cocoon. The ovipositor seems to 
penetrate the aphis skin with little effort. Sometimes it is 
partly withdrawn and inserted again, but only one egg is 
deposited on the host. Occasionally two females may be seen 
to oviposit simultaneously on the same Aphidius; and, 
later, it is not uncommon to find two or three young larvae, 
but only one of the latter reaches maturity, and two imagos 
were never reared from the same cocoon. 
