40 F. SUMICHRAST. 



show themselves in houses at evening in numbers, attracted by the h'^ht, 

 at the time of the first rains, and their appearance generally coincides 

 with the redoubled activity which one then remarks among the tepegnati. 

 The most characteristic trait of the ants of this genus consists in the 

 inroads or migrations which they undertake at undetermined epochs, 

 but in relation, it appears to me, with the atmospheric changes. What 

 traveller, passing over the tierra calknte^' has not encountered tlie 

 phalanxes of ti'jjeguas upon the paths of the primitive foi'ests? What 

 inhabitant of these countries has not, at least once, been unpleasantly 

 torn from the arras of sleep by the invasion of his domicile by a black 

 army of the soldados? 



The purpose of these expeditions ofUcifon is, without doubt, multiple, 

 for the circumstance that these sorties, as one may call them, coincide 

 more often with a change of season, hardly permits one to consider 

 them exclusively as simple razzias undertaken at the expense of other 

 insects. One can believe them to be sometimes expeditions of pillage, 

 sometimes changes of domicile, veritfible migrations. I believe that the 

 following facts, which passed under my observation at the hacienda of 

 Potrero, near Cordova, at the end of September of the past year, show 

 proof of this. During about three months, a colony of soldados (No. 4) 

 had been domiciled under a little bridge formed by some rough trunks 

 of trees bound together by a heap of vegetable mould. The continual 

 excavation which engaged the ants on the under side of the bridge, 

 threatened to cause the disappearance of all the earth which covered 

 the flooring. Every day I watched these labors in the hope of discov- 

 ering at la.st the interior of the formicary, but this hope was disap- 

 pointed, for on the oOth September, in the morning, I found the nest 

 completely abandoned. Its inhabitants did not return until about four 

 months later and this reappearance which was of short duration, was 

 followed almost immediately by a visit which these insects made to my 

 habitation, on the 12th of February, in the night. I have made simi- 

 lar observations in regard to another species (No. 36), and think I can 

 conclude that the JEciton, at least the two species in question, are in 

 the habit of forming temporary nests or habitations for themselves, 

 which they abandon from time to time, distinct from those where are 

 found the reproducing sexes, and where is the place of the growth of 

 the larvae and their metamorphoses. 



The nests are found in cool and shady places in great woods or among 



•s Tropicul region. 



