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XIV. Experiments on some Camivoroiis Insects, especially 

 the Driver Ant Dorylus; and with hiitterjlies' eggs 

 as preg. By C. F. M. Swynnerton, F.L.S., F.E.S. 



[Read May 5th, 1915.] 



I HAVE experimented at one time or another during the 

 past few years in the food-preferences of various carni- 

 vorous insects. I include in the present paper only my 

 experiments on driver-ants, and those in which insects' 

 eggs were used as prey. 



The driver-ants employed were Dorylus (Anomma) 

 nigricans, Illig., var. molestus, Gerst., abundant on and 

 about Mount Chirinda in S.E. Rhodesia. In the wet 

 season (November to April) the collector comes across 

 columns of them, particularly in dense forest, where the 

 first intimation of their presence very frequently consists 

 in sudden sharp bites all over his legs — or hers ; for on 

 two or three occasions some lady whom I have been escort- 

 ing through Chirinda has disappeared suddenly into the 

 undergrowth, and I have myself had to seek out some 

 suitable spot further on in which to await her. I say 

 " suitable " advisedly, for once, while striving to free 

 myself of the intruders, I found them literally swarming 

 all over me, and reahsed too late that in my haste I had 

 sat down to search for them in another part of the same 

 highly populous column. 



The main column sometimes marches as many as twelve 

 or fourteen abreast : I do not of course mean to imply 

 that the ants are in definite lines. It is margined on 

 each side, however, by a line, serried or broken, of grenadier- 

 sized guards, each facing outwards with great uphfted 

 mandibles or patrolling about on the flanks. Within 

 the column there is usually a current in both directions, 

 but very commonly mainly in one; and smaller "loop" 

 columns help to prevent congestion and to serve, appar- 

 ently, other special purposes. Over a foot, or, it may be, 

 much more, of the ground on each side wander scattered 

 stragglers that seize on any potential prey, from a minute 

 beetle to a cow, that is so foolhardy as to approach them, 

 and, aided, when struggling attracts attention, by the 



TRANS. ENT. SOC. LOND. 1915. — PARTS III, IV. (JUNE) 



