The Naturalist in Nicaragua Part 21

Total: 242 species.

Omitting the peculiar species and those generally distributed in Tropical America, we have thus forty-three that are found in Chontales and in Mexico or the United States, and sixty-one that are found in Chontales and countries lying to the southward. The preponderance of southern forms is not so great as in the birds, but when we reflect on the large number of peculiar species, and that the Longicorns of the Atlantic slope of Costa Rica are yet scarcely known, it appears likely that many of the Chontales species will be found ranging southward across the San Juan river, and that the Insect fauna will be shown to have the same relations as the Bird fauna; for, as the Atlantic forest continues unbroken much further southward than northward, so will the insects peculiar to the forest region have a greater range in that direction.

Mr. Hollick has beautifully drawn on wood a few of the characteristic Longicorns of Chontales, all of them, with one exception (Polyrhaphis fabricii), being as yet only known from that province, but probably extending into Costa Rica.

One of these, the lovely little Cosmisoma t.i.tania, Number 7 in Plate 25, has been appropriately named after the Queen of the Fairies by Mr. Bates. It was first found by Mr. Janson, junior, who came out to Chontales purposely to collect insects; and I afterwards obtained it in great numbers. The use of the curious brushes on the antennae is not known. Another longicorn, about the same size (Coremia hirtipes), has its two hindmost legs greatly lengthened, and furnished with brushes: one I saw on a branch was flourishing these in the air, and I thought at first they were two black flies hovering over the branch, my attention being taken from the body of the beetle by the movement of the brushes.

Another fine longicorn, figured in Plate 25, Deliathis nivea, looks as if made of pure white porcelain spotted with black. It is a rare beetle, one or two specimens each season being generally all that are taken. It is usually found on the leaves of young trees from twelve to twenty feet from the ground. I have taken the rather heavy-bodied female by throwing a stone at it and causing it to fall within reach, but the male is more active on the wing, and it was long before I obtained a specimen.

(PLATE 26. LEAF INSECT.)

(PLATE 27. MOSS INSECT.)

Amongst the insects of Chontales none are more worthy of notice than the many curious species of Orthoptera that look like green and faded leaves of trees. I have already described one species that resembles a green leaf, and so much so that it even deceived the acute senses of the foraging ants; other species, belonging to a closely-related genus (Pterochroza), imitate leaves in every stage of decay, some being faded-green, blotched with yellow; others, as in the species figured, resemble a brown withered leaf, the resemblance being increased by a transparent hole through both wings that looks like a piece taken out of the leaf. In many b.u.t.terflies that resemble leaves on the under side of their wings, the wings being raised and closed together when at rest so as to hide the bright colours of the upper surface, there are similar transparent spots that imitate holes; and others again are jagged at the edge, as if pieces had been taken out of them. Many chrysalides also have mirror-like spots that resemble holes; and one that I found hanging from the under side of a leaf had a real hole through it, formed by a horn that projected from the thorax and doubled back to the body, leaving a s.p.a.ce between. Another insect, of which I only found two specimens, had a wonderful resemblance to a piece of moss, amongst which it concealed itself in the daytime, and was not to be distinguished except when accidentally shaken out. It is the larval stage of a species of Phasma.

The extraordinary perfection of these mimetic resemblances is most wonderful. I have heard this urged as a reason for believing that they could not have been produced by natural selection, because a much less degree of resemblance would have protected the mimetic species. To this it may be answered, that natural selection not only tends to pick out and preserve the forms that have protective resemblances, but to increase the perceptions of the predatory species of insects and birds, so that there is a continual progression towards a perfectly mimetic form. This progressive improvement in means of defence and of attack may be ill.u.s.trated in this way. Suppose a number of not very swift hares and a number of slow-running dogs were placed on an island where there was plenty of food for the hares but none for the dogs, except the hares they could catch; the slowest of the hares would be first killed, and the swifter preserved. Then the slowest-running dogs would suffer, and having less food than the fleeter ones, would have least chance of living, and the swiftest dogs would be preserved; thus the fleetness of both dogs and hares would be gradually but surely perfected by natural selection, until the greatest speed was reached that it was possible for them to attain. I have in this supposed example confined myself to the question of speed alone, but in reality other means of pursuit and of escape would come into play and be improved. The dogs might increase in cunning, or combine together to work in couples or in packs by the same selective process; and the hares on their part might acquire means of concealment or stratagem to elude their enemies; but, on both sides, the improvement would be progressive until the highest form of excellence was reached. Viewed in this light, the wonderful perfection of mimetic forms is a natural consequence of the selection of the individuals that, on the one side, were more and more mimetic, and on the other (that of their enemies) more and more able to penetrate through the a.s.sumed disguises. It has doubtless happened in some cases that species, having many foes, have entirely thrown off some of them through the disguises they have been brought to a.s.sume, but others they still cannot elude.

Since Mr. Bates first brought forward the theory of mimetic resemblances its importance has been more and more demonstrated, as it has been found how very largely animal life has been influenced in form and colour by the natural selection of the varieties that were preserved from their enemies, or enabled to approach their prey, through the resemblance they bore to something else. So general are these deceptive resemblances throughout nature, that it is often difficult to determine whether s.e.xual preferences or the preservation of mimetic forms has been most potent in moulding the form and coloration of species, and in some the two forces are seen to be opposed in their operation. Thus in some b.u.t.terflies that mimic the Heliconidae, the females only are mimetic, the males retaining the normal form and coloration of the group to which they belong. In such cases it appears as if the females have not been checked in gradually a.s.suming the disguise they wear, and it is important that they should be protected, as they are more exposed to destruction while seeking for places to deposit their eggs; but that both s.e.xes should not have inherited the change in form and colour when it would have been beneficial to both can only be explained, I think, on the supposition that the females had a choice of mates and preferred those that retained the primordial appearance of the group. This view is supported by the fact that many of the males of the mimetic Leptalides have the upper half of the lower wing of a pure white, whilst all the rest of the wings is barred and spotted with black, red, and yellow, like the species they mimic. The females have not this white patch, and the males usually conceal it by covering it with the upper wing, so that I cannot imagine its being of any other use to them excepting as an attraction in courtship, to exhibit to the females, and thus gratify a deep-seated preference for the normal colour of the order to which the Leptalides belong.

I finally left the mines September 6th, 1872, on my way to England.

I was accompanied through the forest by several of the mining officials. Though glad to return to Europe, it was not without some feeling of regret that I rode for the last time through the forest where I had so often wandered during the years I had been at Santo Domingo. The woods had become as familiar to me as home scenes. No more should I see the white-headed ruby humming-bird come darting down the brook, chasing away the green-throat from its bathing-place; no more watch the flocks of many-coloured birds hunting the insects in the forests, or admire the wonderful instincts of the tropical ants. I listened with pleasure to the last hoa.r.s.e cries of the mot-mots, and tried to impress on my memory the curious forms of vegetation--the palms, the gigantic arums, the tangled lianas, and perching epiphytes.

After reaching Pital I rode rapidly over the savannahs, where the swallows were skimming over the top of the long gra.s.s to frighten up the insects which rested there. After another flounder across the San Jose plains, I reached San Ubaldo without incident, excepting a tumble with my mule in the mud. Much of the land between Pital and the lake is well fitted for the cultivation of maize, sugar, and plantains, and near the river at Acoyapo the soil is very fertile. Little of it is occupied, and it is open to any one to squat down on it and fence it in. All that is required is that the form shall be gone through of obtaining permission from the alcalde of the township, which is never refused. Nicaragua offers a tempting field for the emigrant, but there are some other considerations which should not be lost sight of. When a man finds he can live easily without much work, that all his neighbours are contented with the scantiest clothing, the coa.r.s.est food, and the poorest dwellings, he is very apt to fall into the same slothful habits. Even if he himself has innate energy enough to ward off the insidious foe, he will see his children growing up exposed to all the temptations to lead an easy life that a tropical climate offers, and without any example of industry or enterprise around them to arouse or cultivate a spirit of emulation. The consequence is that nearly all the foreign settlers in Nicaragua from amongst the European and North American labouring cla.s.ses have fallen into the same lazy habits as the Nicaraguans, and whenever I have been inclined to blame the natives for their indolence, some recollection of a fellow-countryman who has succ.u.mbed to the same influences has arrested my harsher judgment. I cannot recommend Nicaragua, with all its natural wealth, its perpetual summer, its magnificent lakes, and its teeming soil, as a place of emigration for isolated families, and even for larger schemes of colonisation I do not think it so suitable as our own colonies and the United States. A large body of emigrants would carry with them the healthful influence of the good and industrious, and the spirit of emulation and progress might be preserved if the community could be kept together, but I fear this could not be. After a while the tastes of one individual would lead in one, those of another in an opposite direction. Where all were free to choose, the idle would go away from the influences that urged them to industry, the sensual from the restraints of morality. Many will, however, smile at the objection I have to emigration to Nicaragua, when they perceive that it is founded only on the ease with which people can live in plenty there. There is one form of colonisation that will be successful, and that is the gradual moving down southward of the people of the United States. When the destiny of Mexico is fulfilled, with one stride the Anglo-American will bound to the Isthmus of Panama, and Central America will be filled with cattle estates, and with coffee, sugar, indigo, cotton, and cacao plantations. Railways will then keep up a healthful and continuous intercourse with the enterprising North, and the sluggard and the sensual will not be able to stand before the compet.i.tion of the vigorous and virtuous. Nor will the Anglo-American long be stayed by the Isthmus in his progress southward. Unless some such catastrophe happens as a few years ago threatened to cover North America with standing armies as in Europe, which G.o.d forbid, not many centuries will roll over before the English language will be spoken from the frozen soil of the far north to Tierra del Fuego in the south.

The fine steamer that the enterprise of Mr. Hollenbeck had placed on the lake, and which he had named the "Elizabeth" after his amiable wife, had been wrecked a short time before I left the country, and Mr. Hollenbeck's own health had greatly suffered by the labours he undertook in endeavouring to get the vessel off the sunken rock on which it had struck. Notwithstanding this and other misfortunes, enough to try a man's mettle to its foundation, his native pluck carried him through all his difficulties, and he was away to the States to get new vessels and blow another blast at fortune's iron gates. Whilst I write these last few pages I learn that a new steamer ploughs the lake, and that his transit service is again in complete working order. Success attend him.

The result of the wreck of the "Elizabeth", so far as I was concerned, was that I had to take a pa.s.sage down the lake to San Carlos in a bungo packet, so full as to necessitate closer acquaintanceship with many amiable Nicaraguans than was agreeable to my insular prejudices. When in the middle of the night an old woman tried to roll me off the soft plank I had found for myself into a litter of crying babies, I indulged in some bitter reflections on the race, that, I am happy to say, were as transitory as the inconvenience to which I was put. At San Carlos we changed to the river steamer under my old friend Captain Birdsall. As I have already described the scenery of the San Juan in the account of my journey up, I shall not repeat the story, but simply state that we reached Greytown on the 11th September, and on the 16th embarked on the West Indian Mail Packet. I arrived in England within a month, to find my native town (Newcastle) wealthier and dirtier than ever, with thousands of furnaces belching out smoke and poisonous gases; to find the people of England fretting about the probable exhaustion of her coal-fields in a few hundred years, actually dreading the time when she will no longer be the smithy of the world, but the centre of the science, philosophy, literature, and art of the Anglo-Saxon race--that race whose sons all over the globe will then look up to her with loving reverence as the mother of nations, the coloniser of the world, the pioneer of freedom, progress, and morality.