It was not always easy to recognize what pasturage the mules would accept as good.  One afternoon we pitched camp by a tiny rivulet, in the midst of the scrubby upland forest; a camp, by the way, where the piums, the small, biting flies, were a torment during the hours of daylight, while after dark their places were more than taken by the diminutive gnats which the Brazilians expressively term “polvora,” or powder, and which get through the smallest meshes of a mosquito-net.  The feed was so scanty, and the cover so dense, at this spot that I thought we would have great difficulty in gathering the mules next morning.  But we did not.  A few hours later, in the afternoon, we camped by a beautiful open meadow; on one side ran a rapid brook, with a waterfall eight feet high, under which we bathed and swam.  Here the feed looked so good that we all expressed pleasure.  But the mules did not like it, and after nightfall they hiked back on the trail, and it was a long and arduous work to gather them next morning.

I have touched above on the insect pests.  Men unused to the South American wilderness speak with awe of the danger therein from jaguars, crocodiles, and poisonous snakes.  In reality, the danger from these sources is trivial, much less than the danger of being run down by an automobile at home.  But at times the torment of insect plagues can hardly be exaggerated.  There are many different species of mosquitoes, some of them bearers of disease.  There are many different kinds of small, biting flies and gnats, loosely grouped together under various titles.  The ones more especially called piums by my companions were somewhat like our northern black flies.  They gorged themselves with blood.  At the moment their bites did not hurt, but they left an itching scar.  Head-nets and gloves are a protection, but are not very comfortable in stifling hot weather.  It is impossible to sleep without mosquito-biers.  When settlers of the right type come into a new land they speedily learn to take the measures necessary to minimize the annoyance caused by all these pests.  Those that are winged have plenty of kinsfolk in so much of the northern continent as has not yet been subdued by man.  But the most noxious of the South American ants have, thank heaven, no representatives in North America.  At the camp of the piums a column of the carnivorous foraging ants made its appearance before nightfall, and for a time we feared it might put us out of our tents, for it went straight through camp, between the kitchen-tent and our own sleeping tents.  However, the column turned neither to the right nor the left, streaming uninterruptedly past for several hours, and doing no damage except to the legs of any incautious man who walked near it.