5. If a noise is made as they fly along, they emit a fluid like water, which the agriculturists describe as if they emitted both a liquid and solid excrement, and that they feed on dew; and if any one approaches them with a bent finger, which is gradually straightened, they will remain more quiet than if it is put out straight at once, and will climb up upon the finger; for, from the dimness of their sight, they climb upon it as if it were a moving leaf.
Chapter XXV.
1. Those insects which are not carnivorous, but live upon the juices of living flesh, as lice, fleas, and bugs, produce nits from sexual intercourse; from these nits nothing else is formed. Of these insects the fleas originate in very small portions of corrupted matter, for they are always collected together where there is any dry dung. Bugs[180] proceed from the moisture which collects on the bodies of animals: lice from the flesh of other creatures; for before they appear, they exist in little pimples which do not contain matter: and if these are pricked, the lice[181] escape from them. Some persons have been afflicted with a disease arising from excessive moisture in the body, of which people have died, as they say that Alcmon the poet, and Pherecydes of Syria did.
2. And in some diseases lice are very common. There is a kind of lice, which they call wild, and are harder than the common sort, which are difficult to eradicate from the body. The heads of children are most subject to be infested with lice, and men the least so, for women are more liable to them than men. Those that have lice in the head are less subject to headache. Many other animals are infested with lice: for both birds have them, and those which are called phasiani, unless they dust themselves, are destroyed by them. And so are all those creatures which have feathers with a hollow stem, and those which have hair, except the ass, which has neither lice nor ticks. Oxen have both; sheep and goats have ticks, but no lice; hogs are infested with large, hard lice, and dogs with those which are called cynoraïstæ. All lice originate in the animals that are infested with them. All creatures that have lice, and wash themselves, are more liable to them when they change the water in which they bathe.
3. In the sea is a kind of lice[182] growing on fish; but these do not originate in the fish, but in the mud. Their appearance is that of wood-lice with many feet, except that they have a wide tail. There is one species of marine lice which occur everywhere, and especially infest the trigla. All these creatures are furnished with many legs, are exsanguineous, and insects. The œstrus[183] of the thynnus occurs near the fins: in shape it is like a scorpion, and as large as a spider. In the sea between Cyrene and Egypt, there is a fish called the phtheira, which accompanies the dolphin; it is the fattest of all fish, because it enjoys an abundance of the food which the dolphin hunts for.
Chapter XXVI.
1. There are also other minute animals, as I observed before, some of which occur in wool,[184] and in woollen goods; as the moths, which are produced in the greatest abundance when the wool is dusty, and especially if a spider is enclosed with them, for this creature is thirsty, and dries up any fluid which may be present. This worm also occurs in garments. There is one which occurs in old honeycombs, like the creature which inhabits dry wood: this appears to be the least of all creatures, it is called acari, it is white and small. Others also are found in books,[185] some of which are like those which occur in garments: others are like scorpions;[186] they have no tails, and are very small. And on the whole, they occur in everything, so to say, which from being dry, becomes moist, or being moist, becomes dry, if it has any life in it.
2. There is a little worm which is called xylophthorus,[187] which is no less extraordinary than these animals; for its variegated head is projected beyond its case, and its feet are at the extremity, as in other worms. The rest of the body is contained in a case made of a substance like spider's web, and a dry material on the outside of this; so that it appears to walk about with this attached to it. These creatures are attached to their case, and as a snail to its shell, so the whole of the case is joined to the worm, and it does not fall out of it, but is drawn out of it, as if they were joined together. If a person pulls off the case, the creature dies, and becomes as helpless as a snail without its shell. As time advances, this grub becomes a chrysalis, like a caterpillar, and lies without motion: but the nature of the winged creature that is produced has never been ascertained.
3. The wild figs upon the fig-trees contain a creature called psen;[188] this is at first a little worm, and afterwards having ruptured the case, the psen flies out, and leaves it behind. It then pierces the unripe figs, and causes them not to fall off, wherefore gardeners place wild fruit near the cultivated kinds, and plant the wild and cultivated plants near each other.