Echo, or the noise made by the reverberation of the air, is also injurious to bees, as it dismays them by its redoubled sounds; fogs, also, are noxious to them. Spiders, too, are especially hostile to bees; when they have gone so far as to build their webs within the hive, the death of the whole swarm is the result. The common and ignoble moth,[73] too, that is to be seen fluttering about a burning candle, is deadly to them, and that in more ways than one. It devours the wax, and leaves its ordure behind it, from which the maggot known to us as the “teredo” is produced; besides which, wherever it goes, it drops the down from off its wings, and thereby thickens the threads of the cobwebs. The teredo is also engendered in the wood of the hive, and then it proves especially destructive to the wax. Bees are the victims, also, of their own greediness, for when they glut themselves overmuch with the juices of the flowers, in the spring season more particularly, they are troubled with flux and looseness. Olive oil is fatal[74] to not only bees, but all other insects as well, and more especially if they are placed in the sun, after the head has been immersed in it. Sometimes, too, they themselves are the cause of their own destruction; as, for instance, when they see preparations being made for taking their honey, and immediately fall to devouring it with the greatest avidity. In other respects they are remarkable for their abstemiousness, and they will expel those that are inclined to be prodigal and voracious, no less than those that are sluggish and idle. Their own honey even may be productive of injury to them; for if they are smeared with it on the fore-part of the body, it is fatal to them. Such are the enemies, so numerous are the accidents—and how small a portion of them have I here enumerated!—to which a creature that proves so bountiful to us is exposed. In the appropriate place[75] we will treat of the proper remedies; for the present the nature of them is our subject. CHAP. 22. (20.)—HOW TO KEEP BEES TO THE HIVE.