The Languedocian Sphex has quite another lot. Its prey is a heavy ephippiger—a single morsel representing the whole sum of provender amassed by the other predatory insects bit by bit. What the Cerceris and other strong-flying insects do by dividing their labour is accomplished by a single effort. The weight of the prey rendering flight impossible, it must be brought home with all the delays and fatigue of dragging it along the ground. This one fact obliges her to accommodate the position of her burrow to the chances of the chase: first the prey and then the dwelling. Hence no rendezvous at a general meeting-place; no living among neighbours, no tribes stimulating themselves by mutual example—only isolation where chance has led the Sphex—solitary labour, unenthusiastic, though always conscientious. First of all prey is sought, attacked, and paralysed. Then comes making the burrow. A favourable spot is chosen as near as possible to that where lies the victim, so as to abridge the toil of transport, and the cell of the future larva is rapidly hollowed to receive an egg and food as soon as possible. Such is the very different method shown by all my observations. I will mention the chief of them.
If surprised in its mining, one always finds this Sphex alone—sometimes at the bottom of some dusty niche a fallen stone has left in an old wall—[[141]]sometimes in a shelter formed by a projecting bit of sandstone, such as is sought by the fierce-eyed lizard as a vestibule to its retreat. The sun falls full upon it; the place is a furnace. The soil is extremely easy to hollow, formed as it is by ancient dust which has dropped little by little from the roof. The mandibles, which act as pincers to dig with, and the tarsi, as rakes to clear away, soon hollow the cavity. Then the Sphex flies off, but in a leisurely way, and without any great expenditure of wing power, a manifest sign that the expedition is not a long one. One’s eye can easily follow the insect and discover where it alights, usually some ten yards off. Sometimes it decides to go on foot. It sets out, hurrying to a spot where we will be indiscreet enough to follow, our presence noways troubling it. Having arrived on foot or on the wing it hunts about for a while, as one may conclude from its indecision and short excursions on all sides. It seeks and at last finds, or rather finds anew. The object found is an ephippiger, half-paralysed, but still moving antennæ, tarsi, and ovipositor—a victim which the Sphex certainly poignarded a little while before with several stings, and then left her prey, an embarrassing burden, while she still hesitated as to the choice of a domicile. Perhaps she abandoned it on the very spot of the capture, leaving it rather obvious on a grass tuft the better to find it later, and trusting to her good memory to return where lies the booty, set to work to explore the neighbourhood and find a suitable spot to burrow. This done she came back for the game which was found without much hesitation, and now she prepares to convey it home. [[142]]She bestrides the insect, seizes one or both antennæ and sets off, pulling and dragging with all the strength of loins and jaws.
Sometimes the journey is accomplished at one trial; more frequently she leaves her load and hurries home. Perhaps it occurs to her that the entrance door is not wide enough for this ample morsel, perhaps she bethinks her of some defect of detail that might interfere with provisioning the cell. Yes, she retouches her work, enlarges the doorway, levels the threshold, consolidates the arch, all with a few sweeps of the tarsi. Then she returns to the ephippiger, lying on its back a few paces distant, and drags it on again. But a new idea seems to flash across her lively mind. She had visited the gateway but had not looked within; who knows if all be well there? She hastens back, leaving the ephippiger midway. The interior is visited, and apparently some touches as with a trowel are given by the tarsi, to lend a last finish to the walls. Without lingering over these final touches the Sphex returns to her prey, and harnesses herself to the antennæ. Forward! Will the journey be accomplished this time? I would not answer for it. I have known a Sphex, perhaps more suspicious than others, or more forgetful of the minor details of architecture, set her omissions right or allay her suspicions by abandoning her prey five or six times successively, and hurrying to the burrow, which each time was touched up a little or simply entered. It is true that others go straight home, without even stopping to rest. I must add that when the Sphex comes home to perfect her dwelling, she does not [[143]]fail to give an occasional, distant glance at the ephippiger left on the way, to make sure that nothing touches it. This prudence recalls that of the Scarabæus sacer issuing from the hole which it is digging to feel its dear ball, and bring it a little nearer.
The deduction to be drawn from the facts just stated is evident. Since every Sphex occitanica we surprise while it burrows—be it at the very beginning, at the first stroke of her tarsi in the dust, or later, the dwelling being ready—makes a short expedition on foot or on the wing, and always finds a victim already stabbed, already paralysed, one may conclude with certainty that she first makes her capture, and later burrows, so that the place of capture decides that of the domicile.
This reversal of method which prepares the food before the larder, while previously we saw the larder precede the food, I attribute to the weight of the prey being too great to carry on the wing. It is not that S. occitanica is ill-organised for flight; on the contrary, she can soar splendidly, but her prey would overwhelm her if she depended only on her wings. She needs the support of the ground and must drag her prey, and displays wonderful vigour in doing this. Loaded with prey she always goes on foot, or takes very short flights when these spare time and toil. Let me quote an instance taken from my latest observations on this curious Hymenopteron.
A Sphex appeared suddenly, whence I know not, dragging an ephippiger apparently just caught hard by. As things were she had to burrow, but the position was as bad as possible—a highway, hard as [[144]]stone. There was no time for difficult mining, since the prey must be stored as soon as possible; she needed light soil where the cell could be quickly made. I have already described her favourite soil—dust deposed by years at the bottom of some hole in a wall, or in some little hollow of a rock. The Sphex which I was observing stopped at the foot of a country house with a newly whitewashed façade, and measuring from six to eight metres in height. Instinct told her that under the roof tiles she would find hollows rich in ancient dust. Leaving her prey at the foot of the façade, she flew on to the roof. For some time I saw her seek vainly about. Then, having found a suitable position, she set to work under the hollow of a tile. In ten minutes or a quarter of an hour at most the domicile was ready; she flew down, promptly found the ephippiger, and then had to carry up her prey. Would it be on the wing, as circumstances suggest? Not at all; the Sphex adopted the difficult method of escalading a vertical wall with a surface smoothed by the mason’s trowel and from six to eight metres high. Seeing her take this road, dragging her game between her feet, I thought at first that it was impossible, but was soon reassured as to the outcome of this audacious attempt. Supporting herself by the little roughnesses of the mortar, the vigorous insect, in spite of the embarrassment of her heavy load, made her way up this vertical plane with the same security, the same speed, as on horizontal ground. The top is reached without any hindrance, and the prey provisionally deposited at the edge of the roof on the rounded bark of a tile. While the Sphex was retouching her [[145]]burrow the ill-balanced prey slipped and fell to the foot of the wall. She must begin again, and again by means of an escalade. The same imprudence is repeated; once more left on the curved tile the prey slips and falls to the ground. With a calm which such accidents cannot disturb, the Sphex for the third time hoists the ephippiger by climbing the wall, and, better advised, drags it straight to the bottom of the hole.
If carrying the prey on the wing has not been attempted even in such conditions as the above, it is clear that the Sphex is incapable of flight with so heavy a load. To this impotence we owe the few details of habits which are the subject of this chapter. A prey not too heavy to be carried on the wing makes a semi-sociable species of S. flavipennis—that is to say, one seeking the company of its fellows; a heavy prey impossible to carry through the air renders S. occitanica a species devoted to solitary labour—a kind of savage, disdainful of the solace derived from neighbourhood of one’s fellows. The greater or lesser weight of their prey decides the fundamental character. [[146]]