440 Mr. C. O. faq Whe s Five Years’ Observations 
at Agege (152 ft.), 16 miles N. of Lagos, together with 
2 6 maj. and 21 9 min. of Cremastogaster buchneri, r. 
alligatrix from the carton nest over which the Cecidomyids 
were flying. Also, from Moor Plantation, stealing from 
ants on carton nests—2 ¢ 3 Q taken Aug. 8, 1918; 7 3, 
together with a sample & of the ants, near race alligatriz, 
taken Aug. 10; and 10 ¢ 8 2 taken about August in the 
same year. | 
April 17, 1918.—Your letter of early March arrived 
safely, having been a month on the road, but we are always 
glad when the mail gets here at all. I have not been able 
to send anything for some time, for I have been very busy 
getting in the crops now that the rains have broken. How- 
ever, I hope to get a small collection together soon. I 
think I shall manage to get you some more interesting 
Myrmecophilous Diptera. Last week-end I had to go to 
Agege on my monthly visit, and went as usual round the 
few Cremastogaster nests within reach. I got no Lycaenids, 
but I was able to study the doings of a number of yellowish- 
brown midge-like flies that kept constantly flying over the 
nest and indeed within the labyrinth of the carton. Obser- 
vation as to their exact doings was extremely difficult 
from their colour and from the fact that they didn’t alight 
at all but remained almost lke Syrphids, though not for 
so long at a time. At other times they kept up a dancing 
flight till their immediate object made them at any time 
approach the nest. I was at last able to satisfy myself 
that the objects of their interest were ants that were in 
the act of feeding each other by the usual method of 
regurgitation. Seeing these on the surface of the carton 
or in a crevice of it, one of the tiny flies would immediately 
approach near enough for its head or proboscis to be in 
touch with the ants, and though, from the fact that they 
were rather shy and didn’t actually come to rest, I could 
not actually succeed in seeing them appropriate a share 
of the food by sheer theft, yet I have not the slightest 
doubt but that they did. Harpagomyia doesn’t alight on 
the carton, which is always much too lively, but hunts on 
the stem of the tree over the “run” of the ants. The 
food exchange is quite leisurely and friendly. I brought 
away a few of the flies with me and found them to 
be Nemocerous Diptera—apparently, and if Nemocerous 
Diptera, I regret to say that with much thought and mis- 
giving I can find no family for them except Cecidomyidae, 
a 
