The Hunting Wasps

by Jean-Henri Fabre

In the face of these singular predilections, which seem to have had their limits laid down for them by some master of classification, by a Latreille, for instance, it becomes interesting to investigate whether the Sphex-wasps that are not natives of our country hunt game of the same order. Unfortunately, information on this point is scanty and, in the case of most [[109]]of the species, is lacking altogether. The chief cause of this regrettable lacuna is the superficial method generally adopted. People catch an insect, stick a long pin through it, fix it in the cork-bottomed box, gum a label with a Latin name underneath its feet, and let its history end there. It is not thus that I understand the duties of an entomological biographer. It is no use telling me that this or that species has so many joints to its antennæ, so many nervures to its wings, so many hairs on a region of the belly or thorax; I do not really know the insect until I am acquainted with its manner of life, its instincts and its habits.

And see the immense and luminous advantage which a description of this kind, told in two or three words, would possess over those long descriptive details, sometimes so hard to grasp. Suppose that you wish to make the Languedocian Sphex known to me and you begin by describing the number and distribution of the nervures of the wings; you speak to me of cubital nervures and recurrent nervures. Next comes the insect’s pen-portrait. Black here, rusty red there, smoky brown at the tips of the wings; black velvet in this part, silvery down in that, a smooth surface in a third. It is all very definite and minute: we must do this much justice to the precision and patience [[110]]of the narrator; but it is very long and also it is by no means always clear, so much so that we may be excused if we are not quite able to follow it, even when we are not altogether new to the business. But add to the tedious description merely this: ‘Hunts Ephippigers’; and these two words at once shed light: there is no possibility of my now mistaking my Sphex, for she alone possesses the monopoly of that particular prey. To give this illuminating note, what would be needed? The habit of really observing and of not making entomology consist of so many series of impaled insects.

But let us pass on and examine the little that is known about the hunting methods of the foreign Sphex-wasps. I open Lepeletier de Saint-Fargeau’s[2] Natural History of Hymenoptera and find that, on the other side of the Mediterranean, in our Algerian provinces, the Yellow-winged Sphex and the White-edged Sphex retain the same habits that characterize them here. They capture Orthoptera in the land of palm-trees even as they do in the land of olive-trees. Though separated from the others by the vast width of the sea, the hunting [[111]]compatriots of the Kabyles and the Berbers pursue the same game as their kindred in Provence. I also see that a fourth species, the African Sphex (S. afra), is the scourge of the Locusts in the neighbourhood of Oran. Lastly, I remember reading, I forget where, of a fifth species which also wages war on Locusts in the steppes near the Caspian. Thus, on the borders of the Mediterranean, we have five different species of Sphex, whose larvæ all live on a diet of Orthoptera.

Now let us cross the equator and go right down to the southern hemisphere, to the islands of Mauritius and Réunion: we shall here find not a Sphex, but a closely-allied Wasp of the same tribe, the Compressed Chlorion, hunting the horrible Kakerlak, that ravager of the foodstuffs in the ships and harbours of the colonies. These Kakerlaks are none other than Cockroaches, whereof one species haunts our dwellings. Who does not know the evil-smelling insect, which, thanks to its flat body, like that of a huge Bug, slips at night through the gaps in furniture and the crannies of partitions and invades any place containing provisions to be devoured? This is the Black-beetle of our houses, a disgusting counterpart of the no less disgusting prey beloved of the Chlorion. What is there about the Kakerlak [[112]]to cause him to be selected as a prey by a near cousin of our Sphex-wasps? It is quite simple: with his Bug shape, the Kakerlak also is an Orthopteron, just as much as the Cricket, the Ephippiger or the Locust. From these six examples, the only ones known to me and of such different origins, we might perhaps deduce that all the Sphex hunt Orthoptera. At any rate, without adopting so general a conclusion, we see what the food of their larvæ must be in most cases.

There is a reason for this surprising choice. What is it? What are the grounds for a diet which, within the strict limits of one entomological order, is composed here of stinking Kakerlaks, there of somewhat dry, but highly-flavoured Locusts, elsewhere again of plump Crickets or fat Ephippigers? I confess that I cannot tell, that I am absolutely in the dark; and I leave the problem to others. At the same time, we may observe that the Orthoptera are among insects what the Ruminants are among mammals. Endowed with a mighty paunch and a placid temperament, they graze contentedly and soon put on flesh. They are numerous, widely distributed and slow in movement, which renders them easy to catch; moreover, they are of a large size, making fine heads of game. Who can say if the Sphex-wasps, [[113]]powerful huntresses, requiring big prey, do not find in these Ruminants of the insect world what we ourselves find in our domestic Ruminants, the Sheep and the Ox, peaceable victims yielding plenty of flesh? It is just a possibility, but no more.

I have something better than a possibility to offer in reply to another and no less important question. Do the Orthopteron-eaters ever vary their diet? Should the favourite type of game fall short, can they not accept a different one? Does the Languedocian Sphex consider that there is nothing in the world worth having but fat Ephippigers? Does the White-edged Sphex allow none but Locusts to figure on her table; and the Yellow-winged Sphex none but Crickets? Or, according to time, place and circumstances, does each make up for the lack of her favourite victuals by others more or less equivalent? To ascertain such facts, if they exist, would be of the greatest importance, for they would tell us if the inspirations of instinct are absolute and unchangeable, or if they vary and within what limits. It is true that the cells of one and the same Cerceris contain the most varied species of either the Buprestis or the Weevil group, which shows that the huntress has a great latitude of choice; but this extension of the hunting-fields cannot be [[114]]presumed in the case of the Sphex-wasps, whom I have seen so faithful to an exclusive victim, always the same for each of them, and who moreover find, among the Orthoptera, groups that differ very widely in shape. Nevertheless, I have had the good fortune to come upon one case, one only, of complete change in the larva’s nourishment; and I record it the more willingly in the Sphegian archives inasmuch as such facts, scrupulously observed, will one day form foundation-stones for any one who cares to build up the psychology of instinct on a solid basis.

Here are the facts. The scene is enacted on a towing-path along the Rhône. On one side is the mighty stream, with its roaring waters; on the other is a thick hedge of osiers, willows, and reeds; between the two runs a narrow walk, with a carpet of fine sand. A Yellow-winged Sphex appears, hopping along, dragging her prey. What do I see! The prey is not a Cricket, but a common Acridian, a Locust! And yet the Wasp is really the Sphex with whom I am so familiar, the Yellow-winged Sphex, the keen Cricket-huntress. I can hardly believe the evidence of my own eyes.

The burrow is not far off: the insect enters it and stores away the booty. I sit down, determined to wait for a new expedition, to wait [[115]]hours if necessary, so that I may see if the extraordinary capture is repeated. My sitting attitude makes me take up the whole width of the path. Two raw conscripts heave in sight, their hair newly cut, wearing that inimitable automaton look which the first days of barrack-life bestow. They are chatting together, talking no doubt of home and the girl they left behind them; and each is innocently whittling a willow-switch with his knife. I am seized with a sudden apprehension. Ah, it is no easy matter to experiment on the public road, where, when the long-awaited event occurs at last, the arrival of a wayfarer is likely to disturb or ruin opportunities that may never return! I rise, anxiously, to make way for the conscripts; I stand back in the osier-bed and leave the narrow passage free. To do more would have been unwise. To say, ‘Don’t go this way, my good lads,’ would have made bad worse. They would have suspected some trap hidden under the sand, giving rise to questions to which no reply that I could have made would have sounded satisfactory. Besides, my request would have turned those idlers into lookers-on, very embarrassing company in such studies. I therefore got up without speaking and trusted to my lucky star. Alas and alack, my star betrayed me: the heavy regulation boot came [[116]]straight down upon the ceiling of the Sphex! A shudder ran through me as though I myself had received the impress of the hobnailed sole.

When the conscripts had passed, I proceeded to save what I could of the ruined burrow’s contents. The Sphex was there, crushed and mangled; and with her not only the Locust whom I had seen carried down, but two others as well, making three Locusts in all instead of the usual Crickets. What was the reason of this curious change? Were there no Crickets in the neighbourhood of the burrow and was the distressed Wasp making up for them with Locusts: a case of Hobson’s choice, in fact? I hesitate to believe it, for there was nothing about the neighbourhood to warrant the supposition that the favourite game was absent. Another, luckier than I, will unriddle this new and unknown mystery. The fact remains that the Yellow-winged Sphex, either from imperious necessity or for some reason that escapes me, sometimes replaces her chosen prey, the Cricket, with another prey, the Locust, presenting no external resemblance to the first, but itself also an Orthopteron.

The observer on whose authority Lepeletier de Saint-Fargeau says a word or two touching the habits of this same Sphex witnessed a similar storing away of Locusts in Africa, near [[117]]Oran. He surprised a Yellow-winged Sphex dragging an Acridian along. Was it an accidental case, like that which I witnessed on the banks of the Rhône? Was it an exception or the rule? Can there be a lack of Crickets in the country around Oran and does the Wasp fill their place with Acridians? The force of circumstances compels me to put the question without finding a reply.