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Ch. X.] - BAMBOO THICKETS. 179

hut on the side of the range, where a few bananas and a little maize was grown. Indian women, naked to the Waist, were, as usual, bruising maize, this being their employment from morning to night; whilst the men were sitting about idle. Some mangy-looking dogs set up a loud barking as we approached. To one of them clung a young spider-monkey. A number of parrots also gave evidence of the great fondness the Indians have for animal pets. There is scarcely a house where some bird or beast is not kept ; and the Indian women are very clever in taming birds, probably by their constant kindness and gentleness to them, and by feeding them out of their mouths and fondling them. From near here we had a fine view, and saw that we had come up the side of a wide valley, bounded on the left by the Amerrique range, on the right by high rounded grassy hills, on one of which we could make out the cattle hacienda of La Puerta. Times of trees and bamboo thickets marked the course of numerous brooks that joined lower down and formed the small rivers we had crossed. Ilooking down the valley it opened out into a wide plain, with here and there sharp-topped conical hills, such as abound in Central America, where they appear to have been taken as landmarks by the Indians, as many of the old roads lead past them. Beyond the plain in the grey distance were the waters of the lake and the peaks of Ometepec and Madera. We had now to ascend the side of a ravine, the road, or rather path, being through a bamboo thicket for about a mile, and the bamboos touching our knees on either side, arching close overhead, so that we had to lie on

the mules' necks a great part of the way. Some portiors

of the road are dangerously steep and rocky; but as fully a league in distance is saved by taking this by-path, instead of the main road by way of La Puerta, I generally preferred travelling by it, especially as I often took rare and new beetles on the bushes. I usually, when travelling, carried a net fixed to a short stick, and caught the insects as I passed along, off the leaves, without stopping; so abundant were they, that it was very rare for me to take the shortest journey without finding some new species to add to my collection. On this journey I did not, however, take many insects, as the latter half of the year 1872, for some reason or other, was a very unfavourable season for them. The scarcity of beetles was very remarkable. The wet season set in a little earlier than usual, but I do not think that this caused the dearth of insects, as at Juigalpa, where there had been scarcely any rain, there were very few compared with the two former years. The year before, when the season was nearly as wet, beetles, especially longicorns, had been very abundant; and the first half of 1872 had not been characterised by any scarcity of them. Some of the fine longicorns that appear in April were numerous. No less than five specimens of a large and beautiful one (Dellathis nivea, Bates), white, with black spots, that we considered one of our greatest rarities, were taken in that month. It was not until the end of May that the great scarcity of beetles, compared with their abundance in former years, became apparent. I think all classes of beetles had suffered. Many fine lamellicorns, that were generally numerous, were not seen at all; neither were many species of longicorns, usually common. A fig-tree that I had growing in my garden

Ch. X.] ANIMAL EPIDEMICS. 181

had been much injured by a longicorn (Taeniotes scalaris) in 1870 and 1871, but was not touched in 1872. Butterflies were also scarce, but it was the second season that they had been so. Some ants were affected; in others, such as the leaf-cutter, I noted no perceptible diminution in number. A little ant (Pheidole sp.) that used to swarm on a passion flower which grew over the house, attending on the honey glands, and scale insects, disappeared altogether; and another species (Hypoclinea sp.) that it used to drive away, took its place. A small stinging black ant (Solenopsis sp.), that was a great plague in the houses, was also fortunately scarce. In the beginning of June nearly all the white ants or termites (“Comiens” of the Nicaraguans) died. In some parts of my house they lay in little heaps, just as they dropped from the nests above in the roof, and most of the nests were entirely depopulated. I examined some of the dead termites with a magnifier, but could detect no difference in them, excepting that they seemed a little swollen. That some epidemic prevailed amongst the insects there can be no doubt; and it is curious that it should have attacked so many different species and classes. I am not sure that it was confined to the insects, for there was also a great mortality amongst the fowls, a great number dying from inflammation of the crop, and two large parrots fell victims to the same disease. This disease amongst the birds may not, however, have been connected in any way with that amongst the insects. I recollect that in 1865 there was a somewhat similar mortality amongst the wasps in North Wales. In the autumn of the preceding year they had been exceedingly abundant, and very destructive to the fruit. In the next spring, numerous females that had hybernated commenced making their paper nests, and I anticipated a still greater plague of wasps in the autumn than we had had the year before; but some epidemic carried off nearly all the females before they finished building their nests, and in the autumn scarcely a wasp was to be seen ; I saw also in the Natural History magazines notices of their scarcity in all parts of England. The great mortality amongst the insects of Chontales in 1872 has some bearing on the origin of species, for in times of such great epidemics we may suspect that the gradations that connect extreme forms of the same species may become extinct. Darwin has shown how very slight differences in the colour of the skin and hair are sometimes correlated with great immunity from certain diseases, and from the action of some vegetable poisons, and the attacks of certain parasites.* Any varieties of species of insects that could withstand better than others these great and probably periodical epidemics, would certainly obtain a great advantage over those not so protected ; and thus the survival of one form, and the extinction of another, might be brought about. We see two species of the same genus, as in many insects, differing but little from each other, yet quite distinct, and we ask, why if these have descended from one parent form, do not the innumerable gradations that must have connected them exist also P. There is but one answer; we are ignorant what characters are

* “Descent of Man,” vol. i. p. 242 ; and “Animals and Plants under Cultivation,” vol. ii. pp. 227—230. I have taken the examples given from the same author.

Ch. X.] WATER RESERVOIRS OF PLANTS, 183

of essential value to each species; we do not know why white terriers are more subject than darker coloured ones to the attacks of the fatal distemper; why yellowfleshed peaches in America suffer more from diseases than the white-fleshed varieties; why white chickens are most liable to the gapes ; or why the caterpillars of silkworms, which produce white cocoons, are not attacked by fungus, so much as those that produce yellow cocoons P. Yet in all these cases, and many others, it has been shown that immunity from disease is correlated with some slight difference in colour or structure, but as to the cause of that immunity we are entirely ignorant. At last we reached the summit of the range, which is probably not less than three thousand feet above the Sea, and entered on the district of Libertad. Rounded boggy hills covered with grass, Sedgy plants and stunted trees, replaced the dry gravelly soil of the Juigalpa district. The low trees bore innumerable epiphytal plants on their trunks and boughs. Many of these are species of Tillandsia, which sit perched up on the small branches like birds. They have sheathy leaves that hold at their base a supply of water that must be very useful to them in the dry season. Insects get drowned in this water, and the plants may derive some nourishment from their decomposing bodies, but I believe the principal object is to obtain a supply of moisture, as the roots of the plants do not hang down to the ground, like those of many other epiphytes in the tropics, nor are they provided with bulbs like the orchids. Some plants that hold liquids in cup-shaped leaves are simply into traps, many of them growing in bogs, where the

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