98 Psyche [June 



THE STANFORD EXPEDITION TO BRAZIL, 1911. 



J. C. Branxer, Director. 



NOTE ON A GUEST OF EC I TON HAMATVM FABR. 



By William M, Mann, 

 Bussey Institution, Harvard University. 



In 1908 Dr. Nils Holmgren described as Mimopria ecitonophila, 

 a remarkable wingless Proctotrupid which was taken with a col- 

 umn of the legionary ant, Eciton hcnnatum Fabr., at Chaquimayo, 

 Prov. de Carabaya, in Peru.^ 



In September, 1911, at Porto Velho, on the Rio Madeira, in 

 Brazil, I had opportunity to observe living specimen^ of this inter- 

 esting ecitonophile. The host ant was one of the most abundant 

 in that vicinity and almost certainly to be found during a morn- 

 ing's walk through the woods. It travels in immense armies and 

 the large size and bright color of the individuals make the columns 

 very conspicuous. One extraordinarily large army remained in 

 one circumscribed locality in the woods near Porto Velho for two 

 days, during which time one could walk scarcely a dozen yards 

 along the trail without meeting individuals. Small columns were 

 seen ascending the highest trees, and returning laden with the 

 larvae, pupse, and even a.dults of other ants, from arboreal nests 

 that they had raided. It was interesting to note that they brought 

 down adults of Dolichoderus lugens, while other adult ants, as Cryp- 

 tocerus, were not molested, and the Cremastogasters were always 

 avoided, even when encountered by a column. 



Unlike some of the other Ecitons, hamatum is readily observed. 

 The species travels above ground, often using the top of a log as 

 a runway, and at such times one could sit by the log and watch 

 the column cjuite comfortably, the only drawback being the fran- 

 tic haste vnili which the ants marched along. The only other ob- 

 jection one could have to hamatum was the scarcity of guests. I 

 watched many columns before finding any iniquilines. This was 

 very disappointing, for many Ecitons are known not only to be 



^ Uber einige myrmecophile Insekten aus Bolivia und Peru. Zoolog. Anzeiger. Bd. XXXIII 

 No. 11, p. 337-349 



