( ,exeyi, ) 
generally pursue it at a distance of about half an inch, but 
backing away directly the ant turned towards it. 
“ Other flies, having rested motionless a few minutes, flew 
up and poised themselves on the wing over the ants, but, 
immediately the drivers realised their presence and stretched 
out towards them with widely opened mandibles, flew again 
to a place of rest. Eventually I saw a Muscid stalking a 
minor ant which had strayed from the main body carrying 
a pupa in its jaws. Suddenly the fly rushed forward, and it 
must have driven its proboscis, which seems to me armed 
with strong bristles, into the pupa, for the ant was brought to 
a standstill with a sharp jerk. 
‘“‘ Then ensued a tug-of-war between ant and fly fastened on 
at opposite ends of the pupa, but neither had the advantage 
till, as it seemed to me, the ant must have got annoyed and 
oosening its hold rushed towards the fly, which of course 
instantly flew off with the pupa, and this it proceeded to suck 
on the ground about a foot away from the ants. It allowed 
me to get quite close before taking to the wing with its prey, 
and it settled again two or three feet further off and became 
so preoccupied with its meal that it fell an easy victim to my 
net. 
‘“T then carefully watched a fly hovering over the ant- 
column. It suddenly swooped down and rose instantly with 
an ant pupa, with the driver that had been carrying it still 
hanging on, fixed to its proboscis. The fly carried this burden 
for about a foot then dropped it and alighted on the ground 
near by. The ant started to run away with the pupa, but the 
fly pursued it, again impaled the pupa and started a tug-of-war 
with the ant. Neither side had any advantage, and then the 
fly rose again about three feet into the air with the pupa and 
ant and after a flight of about eighteen inches let them fall. 
The ant being discomposed by this procedure let go of the 
pupa, and no sooner had it done so than the fly seized it and, 
flying off with it triumphantly, settled near by and proceeded 
as in the previous case to suck the prey. This one again fell 
easily to my net, so that the flies are evidently keenly alert 
only when in the immediate vicinity of the ants. I subse- 
quently noticed that the Diptera seemed to have certain 
