78 THE NATURALIST IX NICARAGUA. [Ch, V. 



entirely deserted, I afterwards found that when much 

 disturbed, and many of the ants destroyed, the survivors 

 migrate to a new locality. I do not doubt that some of 

 the leading minds in this formicarium recollected the nest 

 of the year before, and directed the migration to it. 



Don Francisco Yelasquez informed me, in 1870, that 

 he had a powder which made the ants mad, so that they 

 bit and destroyed each other. He gave me a little of it, 

 and it proved to be corrosive sublimate. I made several 

 trials of it, and found it most efficacious in turning a 

 large column of the ants. A little of it sprinkled across 

 one of their paths in dry weather has a most surprising 

 effect. As soon as one of the ants touches the white 

 powder, it commences to run about wildly, and to attack 

 any other ant it comes across. In a couple of hours, 

 round balls of the ants will be found all biting each other ; 

 and numerous individuals will be seen bitten completely 

 in two, whilst others have lost some of their legs or 

 antennae. News of the commotion is carried to the formi- 

 carium, and huge fellows, measuring three-quarters of an 

 inch in length, that only come out of the nest during a 

 migration or an attack on the nest or one of the working- 

 columns, are seen stalking down with a determined air, 

 as if they would soon right matters. As soon, however, 

 as they have touched the sublimate, all their stateliness 

 leaves them : they rush about ; their legs are seized 

 hold of by some of the smaller ants already affected by 

 the poison ; and they themselves begin to bite, and in 

 short time become the centre of fresh balls of rabid ants. 

 The sublimate can only be used effectively in dry 

 weather. At Colon I found the Americans using coal 

 tar, which they spread across their paths when any of 



