Personal Narrative of Travels to the Equinoctial Regions of America, During the Years 1799-1804, Vol.2 — Chapter 2.20, Part 5

After having spent two days near the cataract of Atures, we were not sorry when our boat was reladen, and we were enabled to leave a spot where the temperature of the air is generally by day twenty-nine degrees, and by night twenty-six degrees, of the centigrade thermometer.

This temperature seemed to us to be still much more elevated, from the feeling of heat which we experienced.

The want of concordance between the instruments and the sensations must be attributed to the continual irritation of the skin excited by the mosquitos.

An atmosphere filled with venomous insects always appears to be more heated than it is in reality.

We were horribly tormented in the day by mosquitos and the jejen, a small venomous fly (simulium), and at night by the zancudos, a large species of gnat, dreaded even by the natives.

Our hands began to swell considerably, and this swelling increased daily till our arrival on the banks of the Temi.

The means that are employed to escape from these little plagues are very extraordinary.

The good missionary Bernardo Zea, who passed his life tormented by mosquitos, had constructed near the church, on a scaffolding of trunks of palm-trees, a small apartment, in which we breathed more freely.

To this we went up in the evening, by means of a ladder, to dry our plants and write our journal.

The missionary had justly observed, that the insects abounded more particularly in the lowest strata of the atmosphere, that which reaches from the ground to the height of twelve or fifteen feet.

At Maypures the Indians quit the village at night, to go and sleep on the little islets in the midst of the cataracts.

There they enjoy some rest; the mosquitoes appearing to shun air loaded with vapours.

We found everywhere fewer in the middle of the river than near its banks; and thus less is suffered in descending the Orinoco than in going up in a boat.

Persons who have not navigated the great rivers of equinoctial America, for instance, the Orinoco and the Magdalena, can scarcely conceive how, at every instant, without intermission, you may be tormented by insects flying in the air; and how the multitude of these little animals may render vast regions almost uninhabitable.

Whatever fortitude be exercised to endure pain without complaint, whatever interest may be felt in the objects of scientific research, it is impossible not to be constantly disturbed by the mosquitos, zancudos, jejens, and tempraneros, that cover the face and hands, pierce the clothes with their long needle-formed suckers, and getting into the mouth and nostrils, occasion coughing and sneezing whenever any attempt is made to speak in the open air.

In the missions of the Orinoco, in the villages on the banks of the river, surrounded by immense forests, the plaga de las moscas, or the plague of the mosquitos, affords an inexhaustible subject of conversation.

When two persons meet in the morning, the first questions they address to each other are: How did you find the zancudos during the night?

How are we to-day for the mosquitos?

* (* Que le han parecido los zancudos de noche?

Como stamos hoy de mosquitos?

) These questions remind us of a Chinese form of politeness, which indicates the ancient state of the country where it took birth.

Salutations were made heretofore in the Celestial empire in the following words, vou-to-hou, Have you been incommoded in the night by the serpents?

The geographical distribution of the insects of the family of tipulae presents very remarkable phenomena.

It does not appear to depend solely on heat of climate, excess of humidity, or the thickness of forests, but on local circumstances that are difficult to characterise.

It may be observed that the plague of mosquitos and zancudos is not so general in the torrid zone as is commonly believed.

On the table-lands elevated more than four hundred toises above the level of the ocean, in the very dry plains remote from the beds of great rivers (for instance, at Cumana and Calabozo), there are not sensibly more gnats than in the most populous parts of Europe.

They are perceived to augment enormously at Nueva Barcelona, and more to the west, on the coast that extends towards Cape Codera.

Between the little harbour of Higuerote and the mouth of the Rio Unare, the wretched inhabitants are accustomed to stretch themselves on the ground, and pass the night buried in the sand three or four inches deep, leaving out the head only, which they cover with a handkerchief.

You suffer from the sting of insects, but in a manner easy to bear, in descending the Orinoco from Cabruta towards Angostura, and in going up from Cabruta towards Uruana, between the latitudes of 7 and 8 degrees.

But beyond the mouth of the Rio Arauca, after having passed the strait of Baraguan, the scene suddenly changes.

From this spot the traveller may bid farewell to repose.

If he have any poetical remembrance of Dante, he may easily imagine he has entered the citta dolente, and he will seem to read on the granite rocks of Baraguan these lines of the Inferno: Noi sem venuti al luogo, ov' i' t'ho detto Che tu vedrai le genti dolorose.

The lower strata of air, from the surface of the ground to the height of fifteen or twenty feet, are absolutely filled with venomous insects.

If in an obscure spot, for instance in the grottos of the cataracts formed by superincumbent blocks of granite, you direct your eyes toward the opening enlightened by the sun, you see clouds of mosquitos more or less thick.

At the mission of San Borja, the suffering from mosquitos is greater than at Carichana; but in the Raudales, at Atures, and above all at Maypures, this suffering may be said to attain its maximum.

I doubt whether there be a country upon earth where man is exposed to more cruel torments in the rainy season.

Having passed the fifth degree of latitude, you are somewhat less stung; but on the Upper Orinoco the stings are more painful, because the heat and the absolute want of wind render the air more burning and more irritating in its contact with the skin.

"How comfortable must people be in the moon!"

said a Salive Indian to Father Gumilla; "she looks so beautiful and so clear, that she must be free from mosquitos."

These words, which denote the infancy of a people, are very remarkable.

The satellite of the earth appears to all savage nations the abode of the blessed, the country of abundance.

The Esquimaux, who counts among his riches a plank or trunk of a tree, thrown by the currents on a coast destitute of vegetation, sees in the moon plains covered with forests; the Indian of the forests of Orinoco there beholds open savannahs, where the inhabitants are never stung by mosquitos.

After proceeding further to the south, where the system of yellowish-brown waters commences,* (* Generally called black waters, aguas negras.

) on the banks of the Atabapo, the Tuni, the Tuamini, and the Rio Negro, we enjoyed an unexpected repose.

These rivers, like the Orinoco, cross thick forests, but the tipulary insects, as well as the crocodiles, shun the proximity of the black waters.

Possibly these waters, which are a little colder, and chemically different from the white waters, are adverse to the larvae of tipulary insects and gnats, which may be considered as real aquatic animals.

Some small rivers, the colour of which is deep blue, or yellowish-brown (as the Toparo, the Mataveni, and the Zama), are exceptions to the almost general rule of the absence of mosquitos over the black waters.

These three rivers swarm with them; and the Indians themselves fixed our attention on the problematic causes of this phenomenon.

In going down the Rio Negro, we breathed freely at Maroa, Daripe, and San Carlos, villages situated on the boundaries of Brazil.

But this improvement of our situation was of short continuance; our sufferings recommenced as soon as we entered the Cassiquiare.

At Esmeralda, at the eastern extremity of the Upper Orinoco, where ends the known world of the Spaniards, the clouds of mosquitos are almost as thick as at the Great Cataracts.

At Mandavaca we found an old missionary, who told us with an air of sadness, that he had had his twenty years of mosquitos in America*.

(* "Yo tengo mis veinte anos de mosquitos."

) He desired us to look at his legs, that we might be able to tell one day, beyond sea (por alla), what the poor monks suffer in the forests of Cassiquiare.

Every sting leaving a small darkish brown point, his legs were so speckled that it was difficult to recognize the whiteness of his skin through the spots of coagulated blood.

If the insects of the genus Simulium abound in the Cassiquiare, which has white waters, the culices or zancudos are so much the more rare; you scarcely find any there; while on the rivers of black waters, in the Atabapo and the Rio, there are generally some zancudos and no mosquitos.

I have just shown, from my own observations, how much the geographical distribution of venomous insects varies in this labyrinth of rivers with white and black waters.

It were to be wished that a learned entomologist could study on the spot the specific differences of these noxious insects,* which in the torrid zone, in spite of their minute size, act an important point in the economy of nature.

(* The mosquito bovo or tenbiguai; the melero, which always settles upon the eyes; the tempranero, or putchiki; the jejen; the gnat rivau, the great zancudo, or matchaki; the cafafi, etc. ) What appeared to us very remarkable, and is a fact known to all the missionaries, is, that the different species do not associate together, and that at different hours of the day you are stung by distinct species.

Every time that the scene changes, and, to use the simple expression of the missionaries, other insects mount guard, you have a few minutes, often a quarter of an hour, of repose.

The insects that disappear have not their places instantly supplied by their successors.

From half-past-six in the morning till five in the afternoon, the air is filled with mosquitos;

which have not, as some travellers have stated, the form of our gnats,* (* Culex pipiens.

This difference between mosquito (little fly, simulium) and zancudo (gnat, culex) exists in all the Spanish colonies.

The word zancudo signifies long legs, qui tiene las zancas largas.

The mosquitos of the Orinoco are the moustiques; the zancudos are the maringouins of French travellers.

) but that of a small fly.

They are simuliums of the family Nemocera of the system of Latreille.

Their sting is as painful as that of the genus Stomox.

It leaves a little reddish brown spot, which is extravased and coagulated blood, where their proboscis has pierced the skin.

An hour before sunset a species of small gnats, called tempraneros,* because they appear also at sunrise, take the place of the mosquitos.

(* Which appear at an early hour (temprano).

Some persons say, that the zancudo is the same as the tempranero, which returns at night, after hiding itself for some time.

I have doubts of this identity of the species; the pain caused by the sting of the two insects appeared to me different.

) Their presence scarcely lasts an hour and a half; they disappear between six and seven in the evening, or, as they say here, after the Angelus (a la oracion).

After a few minutes' repose, you feel yourself stung by zancudos, another species of gnat with very long legs.

The zancudo, the proboscis of which contains a sharp-pointed sucker, causes the most acute pain, and a swelling that remains several weeks.

Its hum resembles that of the European gnat, but is louder and more prolonged.

The Indians pretend to distinguish the zancudos and the tempraneros by their song; the latter are real twilight insects, while the zancudos are most frequently nocturnal insects, and disappear toward sunrise.

In our way from Carthagena to Santa Fe de Bogota, we observed that between Mompox and Honda, in the valley of the Rio Magdalena, the zancudos darkened the air from eight in the evening till midnight;

that towards midnight they diminished in number, and were hidden for three or four hours; and lastly that they returned in crowds, about four in the morning.

What is the cause of these alternations of motion and rest?

Are these animals fatigued by long flight?

It is rare on the Orinoco to see real gnats by day; while at the Rio Magdalena we were stung night and day, except from noon till about two o'clock.

The zancudos of the two rivers are no doubt of different species.

We have seen that the insects of the tropics everywhere follow a certain standard in the periods at which they alternately arrive and disappear.

At fixed and invariable hours, in the same season, and the same latitude, the air is peopled with new inhabitants, and in a zone where the barometer becomes a clock,* (* By the extreme regularity of the horary variations of the atmospheric pressure.

) where everything proceeds with such admirable regularity, we might guess blindfold the hour of the day or night, by the hum of the insects, and by their stings, the pain of which differs according to the nature of the poison that each species deposits in the wound.

At a period when the geography of animals and of plants had not yet been studied, the analogous species of different climates were often confounded.

It was believed that the pines and ranunculuses, the stags, the rats, and the tipulary insects of the north of Europe, were to be found in Japan, on the ridge of the Andes, and at the Straits of Magellan.

Justly celebrated naturalists have thought that the zancudo of the torrid zone was the gnat of our marshes, become more vigorous, more voracious, and more noxious, under the influence of a burning climate.

This is a very erroneous opinion.

I carefully examined and described upon the spot those zancudos, the stings of which are most tormenting.

In the rivers Magdalena and Guayaquil alone there are five distinct species.

The culices of South America have generally the wings, corslet, and legs of an azure colour, ringed and variegated with a mixture of spots of metallic lustre.

Here as in Europe, the males, which are distinguished by their feathered antennae, are extremely rare; you are seldom stung except by females.

The preponderance of this sex explains the immense increase of the species, each female laying several hundred eggs.

In going up one of the great rivers of America, it is observed, that the appearance of a new species of culex denotes the proximity of a new stream flowing in.

I shall mention an instance of this curious phenomenon.

The Culex lineatus, which belongs to the Cano Tamalamec, is only perceived in the valley of the Rio Grande de la Magdalena, at a league north of the junction of the two rivers; it goes up, but scarcely ever descends the Rio Grande.

It is thus, that, on a principal vein, the appearance of a new substance in the gangue indicates to the miner the neighbourhood of a secondary vein that joins the first.

On recapitulating the observations here recorded, we see, that within the tropics, the mosquitos and zancudos do not rise on the slope of the Cordilleras* toward the temperate region, where the mean heat is below 19 or 20 degrees (* The culex pipiens of Europe does not, like the culex of the torrid zone, shun mountainous places.

Giesecke suffered from these insects in Greenland, at Disco, in latitude 70 degrees.

They are found in Lapland in summer, at three or four hundred toises high, and at a temperature of 11 or 12 degrees.

); and that, with few exceptions, they shun the black waters, and dry and unwooded spots.

* (* Trifling modifications in the waters, or in the air, often appear to prevent the development of the mosquitos.

Mr. Bowdich remarks that there are none at Coomassie, in the kingdom of the Ashantees, though the town is surrounded by marshes, and though the thermometer keeps up between seventeen and twenty-eight centesimal degrees, day and night.

) The atmosphere swarms with them much more in the Upper than in the Lower Orinoco, because in the former the river is surrounded with thick forests on its banks, and the skirts of the forests are not separated from the river by a barren and extensive beach.

The mosquitos diminish on the New Continent with the diminution of the water, and the destruction of the woods; but the effects of these changes are as slow as the progress of cultivation.

The towns of Angostura, Nueva Barcelona, and Mompox, where from the want of police, the streets, the great squares, and the interior of court-yards are overgrown with brushwood, are sadly celebrated for the abundance of zancudos.

People born in the country, whether whites, mulattoes, negroes, or Indians, all suffer from the sting of these insects.

But as cold does not render the north of Europe uninhabitable, so the mosquitos do not prevent men from dwelling in the countries where they abound, provided that, by their situation and government, they afford resources for agriculture and industry.

The inhabitants pass their lives in complaining of the insufferable torment of the mosquitos, yet, notwithstanding these continual complaints, they seek, and even with a sort of predilection, the commercial towns of Mompox, Santa Marta, and Rio de la Hacha.

Such is the force of habit in evils which we suffer every hour of the day, that the three missions of San Borja, Atures, and Esmeralda, where, to make use of an hyperbolical expression of the monks, there are more mosquitos than air,* (* Mas moscas que aire.

) would no doubt become flourishing towns, if the Orinoco afforded planters the same advantages for the exchange of produce, as the Ohio and the Lower Mississippi.

It is a curious fact, that the whites born in the torrid zone may walk barefoot with impunity, in the same apartment where a European recently landed is exposed to the attack of the nigua or chegoe (Pulex penetrans).

This animal, almost invisible to the eye, gets under the toe-nails, and there acquires the size of a small pea, by the quick increase of its eggs, which are placed in a bag under the belly of the insect.

The nigua therefore distinguishes what the most delicate chemical analysis could not distinguish, the cellular membrane and blood of a European from those of a creole white.

The mosquitos, on the contrary, attack equally the natives and the Europeans; but the effects of the sting are different in the two races of men.

The same venomous liquid, deposited in the skin of a copper-coloured man of Indian race, and in that of a white man newly landed, causes no swelling in the former, while in the latter it produces hard blisters, greatly inflamed, and painful for several days; so different is the action on the epidermis, according to the degree of irritability of the organs in different races and different individuals!