DISAPPEARANCE OP MOSQUITOS. 
4C9 
When trayellers judge only by their own sensations they 
differ from each other respecting the abundance of the 
mosquitos as they do respecting the progressive inciease or 
diminution of the temperature. The state of our organs, 
the motion of the air, its degree of humidity or dryness, its 
electric intensity, a thousand circumstances contribute at 
once to make us suffer more or less from the heat and the 
insects. My fellow travellers were unanimously of opinion 
that Esmeralda was more tormented by mosquitos than the 
banks of the Cassiquiare, and even more than the two missions 
of the Great Cataracts ; whilst I, less sensible than they of 
the high temperature of the air, thought that the irritation 
produced by the insects was somewhat less at Esmeralda 
than at the entrance of the Upper Orinoco. On hearing 
the complaints that are made of these tormenting insects in 
hot countries it is difficult to believe that their absence, or 
rather their sudden disappearance, could become a subject 
of inquietude; yet such is the fact. The inhabitants of 
Esmeralda related to us, that in the year 1795, an hour 
before sunset, when the mosquitos usually form a very thick 
cloud, the air was observed to be suddenly free from them. 
During the space of twenty minutes, not one insect was 
perceived, although the sky was cloudless, and no wind 
announced rain. It is necessary to have lived in those 
countries to comprehend the degree of surprise which the 
sudden disappearance of the insects must have produced. 
The inhabitants congratulated each other, and inquired 
whether this state of happiness, this relief from pain (feli- 
cidad y alivio), could be of any duration. But soon, instead 
of enjoying the present, they yielded to chimerical fears, 
and imagined that the order of nature was perverted. Some 
old Indians, the sages of the place, asserted that the disap- 
pearance of the insects must be the precursor of a great 
earthquake. Warm discussions arose ; the least noise amid 
the foliage of the trees was listened to with an attentive 
ear ; and when the air was again filled with mosquitos they 
Were almost hailed with pleasure. We could not guess 
what modification of the atmosphere had caused this pheno- 
menon, which must not be confounded with the periodica] 
replacing of one species of insects by another. 
