The auricles yield a dumpy Louse, wider behind than before and of a dark olive colour. Her most remarkable feature is her sucker, which, folded underneath the insect, sticks out behind, recalling after a fashion a Grasshopper’s oviscapt. What can the puny creatures want with this mechanism? It is a sword, a sabre. Held erect, the implement would prevent any attempt at walking. To drive it into the food-plant, the insect apparently hoists itself on its legs, which correspond in length with the enormous probe. I should like to see this inordinate beak at work. My captives refuse what I give them: leaves and fresh galls. They lie huddled on the plug of cotton-wool which closes the tube. They have business to attend to. They want to get away; but to what? Likewise squat of build, packed, not without a certain prettiness, into the shape of miniature Toads, the Lice from the globular galls are a pale yellowish brown, while those of the folded leaves are greenish black. Neither the first nor the second have beaks of exaggerated length. That extraordinary rostrum, which sticks out behind, and, when at rest, resembles a caudal appendage, recurs in the young Lice from the spindle-shaped galls; but this time the little creature is oblong and its colour is pale green. Let us cut short these dry details. It is enough if we recognize that these five fellow-guests of the terebinth are not of one race following different trades, but separate species. If the earlier generations, which all resemble one another, seemed to bear witness to a specific unity, the family of the winged Lice testifies to the contrary. These thickset insects and these slender ones; these bearers of the rostrum, sometimes of normal length and sometimes fantastically prolonged into the semblance of a caudal beak; these pale-green, olive-green, light-yellow insects are obviously independent forms. A meticulous examination might find here preeminently all the characteristic features of the five categories; but the reader, repelled by prose descriptions, would soon turn the page. Let us pass on. Let us leave the insect laboratory, with its jars and test-tubes; let us go out of doors to see how matters come to pass under natural conditions on the terebinth in the grounds. The galls, frequently inspected during the hottest hours of the day, open before my eyes; the horns are splitting at the top, the globes are opening their sides, the others are parting their lips. The moment the fissure is wide enough the black emigrants appear, without haste, one by one, in absolute composure, despite the fierceness of the sun. The exodus was not accomplished with greater sobriety in the comparative darkness of my study. For a few seconds they linger in the breach; then, shedding a dusty trail from their floury backs, they spread their wings and are off. Their flight, favoured by the least breath of air, promptly carries them to a distance at which I soon lose sight of them.