ISTHMUS OF TEHUANTEPEC 
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can gets out of the way. The householders welcome these visits, as 
the ant army goes through every crack and cranny in the house, killing 
mice, spiders, and insects of all sorts; in fact, making a clean sweep. 
When they call in the middle of the night, and announce their 
arrival by mounting one's bed, and by the most vicious of bites, it is a bit 
sudden, but all one has to do is to get out of the way until their work is 
done, when they depart with the curious rustling noise with which they 
came. Some of these armies march great distances, and have huge nests, 
as much as fifty feet in diameter. 
The rubber tree is not singular in being free from pests — nearly 
all others seem to be equally so. It was a rare thing to see a leaf or 
a petal that had been blighted or eaten by any sort of insect. The reasons 
for this remarkable immunity from the usual pests are not far to seek. 
They will, I think be found in the great abundance of birds, and no doubt 
in the wonderful equilibrium that nature has there established between 
the insects that are destructive to plant life, and the other insects that 
prey upon them. It is to be hoped that this balance may long be pre- 
served. As a matter of caution, it might be well to state that the hunter 
who slaughters birds for their plumage will not find a cordial welcome 
among the Mexican planters. 
In the dry season, which of course was when my visit was made, 
there are but few butterflies and moths but in the rainy season they are 
most abundant. Of these my host had a collection which gave me a won- 
derful insight into the winged beauties in that section. 
