Cuap. IX. FIRE-ANTS. 227 
in the slack currents of the tributaries in the dry season, and the absence 
of the cooling Amazonian trade-wind, which purifies the air along the 
banks of the main river. The trade-wind does not deviate from its 
nearly straight westerly course, so that the branch streams, which run 
generally at right angles to the Amazons, and have a slack current for a 
long distance from their mouths, are left to the horrors of nearly stagnant 
air and water. 
Aveyros may be called the head-quarters of the fire-ant, which might 
be fittingly termed the scourge of this fine river. The Tapajos is nearly 
free from the insect pests of other parts, mosquitoes, sand-flies, motticas 
and piums ; but the formiga de fogo is perhaps a greater plague than all 
the others put together. It is found only on sandy soils in open places, 
and seems to thrive most in the neighbourhood of houses and weedy 
villages such as Aveyros ; it does not occur at all in the shades of the 
forest. I noticed it in most places on the banks of the Amazons, but 
the species is not very common on the main river, and its presence is 
there scarcely noticed, because it does not attack man, and the sting is 
not so virulent as it is in the same species on the banks of the Tapajos. 
Aveyros was deserted a few years before my visit on account of this 
little tormentor, and the inhabitants had only recently returned to their 
houses, thinking its numbers had decreased. _It is a small species of a 
shining reddish colour, not greatly differing from the common red sting- 
ant of our own country (Myrmica rubra), except that the pain and 
irritation caused by its sting are much greater. The soil of the whole 
village is undermined by it : the ground is perforated with the entrances 
to their subterranean galleries, and a little sandy dome occurs here and 
there, where the insects bring their young to receive warmth near the 
surface. The houses are overrun with them ; they dispute every fragment 
of food with the inhabitants, and destroy clothing for the sake of the 
starch. All eatables are obliged to be suspended in baskets from the 
rafters, and the cords well soaked with copaiiba balsam, which is the 
only means known of preventing them from climbing. They seem to 
attack persons out of sheer malice: if we stood for a few moments in 
the street, even at a distance from their nests, we were sure to be 
overrun and severely punished, for the moment an ant touched the 
flesh, he secured himself with his jaws, doubled in his tail, and stung 
with all his might. When we were seated on chairs in the evenings 
in front of the house to enjoy a chat with our neighbours, we had 
stools to support our feet, the legs of which, as well as those of the 
chairs, were well anointed with the balsam. The cords of hammocks 
are obliged to be smeared in the same way to prevent the ants from 
paying sleepers a visit. 
The inhabitants declare that the fire-ant was unknown on the Tapajos 
before the disorders of 1835-6, and believe that the hosts sprang up 
from the blood of the slaughtered Cabanas. They have, doubtless, 
increased since that time, but the cause lies in the depopulation of the 
villages, and the rank growth of weeds in the previously cleared well- 
kept spaces. I have already described the line of sediment formed, on 
the sandy shores lower down theriver, by the dead bodies of the winged 
individuals of this species. The exodus from their nests of the males 
