The effect is overwhelming. For two or three seconds the insect writhes in convulsions and then falls on its side, motionless throughout, save in the ovipositor and the antennae. Nothing stirs so long as the creature is left alone; but, if I tickle it with a hair-pencil, the four hind-legs move sharply and grip the point. As for the fore-legs, smitten in their nerve-centre, they are quite lifeless. The same condition is maintained for three days longer. On the fifth day, the creeping paralysis leaves nothing free but the antennae waving to and fro and the abdomen throbbing and lifting up the ovipositor. On the sixth, the Grasshopper begins to turn brown;she is dead. Except that the vestige of life is more persistent, the case is the same as that of the Decticus. If we can prolong the duration, we shall have the victim of the Sphex.
But first let us look into the effect of a prick administered elsewhere than opposite the thoracic ganglia. I cause a female Ephippiger to be stung in the abdomen, about the middle of the lower surface. The patient does not seem to trouble greatly about her wound: she clambers gallantly up the sides of the bell-jar under which I have placed her; she goes on hopping as before. Better still, she sets about browsing the vine-leaf which I have given her for her consolation. A few hours pass and the whole thing is forgotten. She has made a rapid and complete recovery.
A second is wounded in three places on the abdomen: in the middle and on either side. On the first day, the insect seems to have felt nothing; I see no sign of stiffness in its movements. No doubt it is suffering acutely; but these stoics keep their troubles to themselves. Next day, the Ephippiger drags her legs a little and walks somewhat slowly. Two days more; and, when laid on her back, she is unable to turn over. On the fifth day, she succumbs. This time, Ihave exceeded the dose; the shock of receiving three stabs was too much for her.
And so with the others, down to the sensitive Cricket, who, pricked once in the abdomen, recovers in one day from the painful experience and goes back to her lettuce-leaf. But, if the wound is repeated a few times, death ensues within a more or less short period. I make an exception, among those who pay tribute to my cruel curiosity, of the Rosechafer-grubs, who defy three and four needle-thrusts. They will collapse suddenly and lie outstretched, flabby and lifeless; and, just when I am thinking them dead or paralysed, the hardy creatures will recover consciousness, move along on their backs (This is the usual mode of progression of the Cetonia- or Rosechafer-grub. Cf.
"The Life and Love of the Insect": chapter 11.--Translator's Note.), bury themselves in the mould. I can obtain no precise information from them. True, their thinly scattered cilia and their breastplate of fat form a palisade and a rampart against the sting, which nearly always enters only a little way and that obliquely.
Let us leave these unmanageable ones and keep to the Orthoperon, which is more amenable to experiment. A dagger-thrust, we were saying, kills it if directed upon the ganglia of the thorax; it throws it into a transient state of discomfort if directed upon another point. It is, therefore, by its direct action upon the nervous centres that the poison reveals its formidable properties.
To generalize and say that death is always near at hand when the sting is administered in the thoracic ganglia would be going too far:
it occurs frequently, but there are a good many exceptions, resulting from circumstances impossible to define. I cannot control the direction of the sting, the depth attained, the quantity of poison shed; and the stump of the Bee is very far from making up for my shortcomings. We have here not the cunning sword-play of the predatory insect, but a casual blow, ill-placed and ill-regulated.
Any accident is possible, therefore, from the gravest to the mildest.
Let us mention some of the more interesting.
An adult Praying Mantis (Mantis religiosa, so-called because the toothed fore-legs, in which it catches and kills its prey, adopt, when folded, an attitude resembling that of prayer.--Translator's Note.) is pricked level with the attachment of the predatory legs.
Had the wound been in the centre, I should have witnessed an occurrence which, although I have seen it many times, still arouses my liveliest emotion and surprise. This is the sudden paralysis of the warrior's savage harpoons. No machinery stops more abruptly when the mainspring breaks. As a rule, the inertia of the predatory legs attacks the others in the course of a day or two; and the palsied one dies in less than a week. But the present sting is not in the exact centre. The dart has entered near the base of the right leg, at less than a millimetre (.039 inch.--Translator's Note.) from the median point. That leg is paralysed at once; the other is not; and the insect employs it to the detriment of my unsuspecting fingers, which are pricked to bleeding-point by the spike at the tip. Not until to-morrow is the leg which wounded me to-day rendered motionless. This time, the paralysis goes no farther. The Mantis moves along quite well, with her corselet proudly raised, in her usual attitude; but the predatory fore-arms, instead of being folded against the chest, ready for attack, hang lifeless and open. I keep the cripple for twelve days longer, during which she refuses all nourishment, being incapable of using her tongs to seize the prey and lift it to her mouth. The prolonged abstinence kills her.
Some suffer from locomotor ataxy. My notes recall an Ephippiger who, pricked in the prothorax away from the median line, retained the use of her six limbs without being able to walk or climb for lack of co-ordination in her movements. A singular awkwardness left her wavering between going back and going forward, between turning to the right and turning to the left.
