Angola and the River Congo, vol. 2

by Joachim John Monteiro

It was nothing else than a column of these ants that had passed through the hut and had instantly fastened on the bodies of the sleeping blacks with which it was filled. They fasten their great jaws into the skin so tightly, that their bodies can be pulled off their heads without relaxing their hold. The mandibles must discharge a poisonous fluid into the wound, as their bite feels exactly like a sharp puncture from a red-hot needle, and they always draw blood.

I once unconsciously put my foot upon a column, but luckily only three or four fastened on my ankle and leg, and I shall never forget the sudden and sharp hot bite of the wretches.

There is another kind very abundant on bushes and trees, of a semi-transparent watery-red colour, with long legs; their bite is also very sharp. They build nests by attaching the leaves together with fine white web; these nests are from the size of an apple to that of a hat.

Their food must be principally the fruit and seeds of the plants they are usually found on. Some seeds, particularly those of the india-rubber creeper, I had the greatest difficulty in obtaining ripe, from these ants eating them up whilst green.

A minute red ant, like that which infests our kitchens and houses, is extremely abundant, and is very difficult to keep out of sugar and other provisions; the best way is to place the legs of the table in saucers of vinegar and water, or have safes suspended by a rope, which must be tarred, or they will find their way down. If anything on which they are swarming is placed in the sun, they immediately vanish. A small piece of camphor, tied up in a bit of rag and placed in a sugar-basin or safe, will effectually keep them out, without flavouring the sugar, &c., in the least.

The best and cheapest preventive against the white ant is ordinary petroleum; they will not come near a place where the least trace of its smell exists.

Of other insects the most abundant and worthy of note, besides the mosquitoes already described, are the many species of wasps. One of these, brightly barred with yellow and having a comical habit of dropping down its long legs in a bunch straight under its body as it flies, is the Pelopœus spirifex ([Plate XVI.])—(called “marimbondo” by the natives)—and is one of the large family found in the tropics and called “mud-daubers” from their habit of making clay or mud nests in which they store up spiders and caterpillars as provision for the grubs or larvæ. It is a very singular fact that of the fifty or sixty species known to entomologists, all are males, the females not having yet been discovered. It is supposed that the latter are parasites on other insects, or perhaps in ants’ nests, &c. I have opened many hundreds of the clay cells and invariably found a grub or perfect male insect, or the empty chrysalis of one; and I further ascertained that the male insect does not bring the female in its legs or mouth to lay the egg in the cell, nor does he bring the egg, but the young, hatched grub. I watched one nest being built, and when it was ready, I saw the insect fly away and return and go into it, and on examination I found that it had deposited the small grub at the bottom. In its next journeys it brought spiders till the cell was full of them, when it procured some clay and quickly plastered over the aperture. To procure the spiders it first stabs them with its dreadful sting, and then picks them up and flies away with them to its nest.

Whilst at Bembe, I fortunately witnessed a fight between a large specimen of these wasps and a powerful spider which had built its fine web on my office wall. The spider nearly had the wasp enveloped in its web several times, and by means of its long legs prevented the wasp from reaching its body with its sting, but at last, after a few minutes hard fighting, the wasp managed to stab the spider right in the abdomen, when it instantly curled up its legs and dropped like dead to the ground. The wasp pounced down on it, but I interfered, and picking up the spider placed it under a tumbler to ascertain how long it would live, as I had noticed that the spiders stored in the nests were always alive, although unable to crawl away when taken out. It lived for a week, and, although moving its legs when touched, had no power of locomotion, showing that the poison of the wasp has a strong paralysing effect. I have counted as many as twenty spiders in a single cell, and there are seldom less than three cells together, and sometimes as many as eight or ten.

These wasps are fond of building their nests in the houses, on curtains, behind picture-frames, books, or furniture, and I once found the inside of a harmonium full of them. Each cell is about the size of a thimble; they are very smoothly and prettily made, and a wasp will build one in a day easily. I never found anything else in these cells but spiders and caterpillars.

It is satisfactory to know that these savage destroyers of spiders have in their turn enemies from which they have no escape. These are large, long-bodied, brown flies (Dasylus sp. and Dasypogon sp.) ([Plate XVI.]), with long legs and a very quiet inoffensive look and manner of flying. They settle on the backs of the different species of wasps, their long legs enabling them to keep at such a distance that the wasp cannot reach them with its sting, then insert a long sharp proboscis into the wasp’s back and suck its body dry, when they fly off in search of another. Other beautiful flies of splendent metallic colouring (Stilbum sp.) also prey on the wasps and mud-daubers. These flies again are an easy prey to the numerous insectivorous birds, and thus we get a series of links of the complicated chain of the apparently somewhat cruel law of Nature, by means of which the due proportion of animal life would appear to be principally adjusted, and an undue preponderance of one kind over another prevented.