on the Bionomics of Southern Nigerian Insects. 443 
p. 369] is a large decayed hollow up the inside of which 
is a considerable portion of the carton nest of the ants. 
I found that this hollow simply swarms with them. But 
in addition to these it suddenly struck me that certain 
curious little flies, which I had often seen before on ant- 
trees, but neglected to study, might be the Cecidomyids 
at rest. L had often meant to write you about these 
curious little flies from their habit of resting habitually on 
a silk web not unlike the webs of some spiders. I have 
often seen hundreds of them hanging by their fore-legs, 
rows of them, on such webs, and vaguely thought they 
specialised in spider-webs as a resting-place. Now, how- 
ever, I am in doubt as to the origin of the silk threads, 
and I am seriously wondering whether the flies do not 
make them themselves. I am not sure that they are the 
Cecidomyids yet, but if not they are extremely similar, 
and when disturbed their flight is much the same, except 
that they quickly come to rest again on their silk threads. 
The threads do not appear to be traps for other insects. 
They are too widely separated. The insects at rest 
remind one of birds on telephone wires except that they 
hang down. Though I did find a large bug (dead) resting 
on the threads, I felt sure that it had fallen on to them 
after death and was too big to slip through between the 
“lines.” I readily caught a lot of them by bringing 
together a box and its lid held in either hand. A portion 
of the ““ web ” was included and in a few seconds the little 
flies had hung themselves up. None of them settled on 
the side of the tin. Some of them were hanging with one 
foot on a thread and another on a leg of the nearest neigh- 
bour. To-morrow I hope to have a look at them under 
the microscope to get a view of their proboscis. 
B. Tur Pursvurr oF Living ANTS BY THE EPHYDRID, 
RHYNCHOPSILOPA APICALIS COLLIN, SP. N. (p. 509). 
(Material :—2 $3 9, taken Dee. 25, 1917—Jan. 26, 1918, 
feeding from the anus of dead Cremastogaster ants as 
described in Proc. Ent. Soc., 1918, pp. xxxv, xxxvi, xl.] 
Aug. 25, 1918.—While I was studying these [Ceci- 
domyids], I noticed some of the little “ proctophila ” 
and froze on to one in particular for special observation. 
I am now certain that they actually pursue living ants, 
smaller workers, pursuing them from behind, with apparently 
the same unpleasant object. They appear to select an 
