But the mortality is probably even greater at a still earlier stage, for hosts of spiders’ eggs never hatch at all, and this for two reasons. In the first place, the silk of spiders is a favourite material with many birds for the lining of their nests, and many of them use the cocoons for this purpose. Secondly, there are numerous Ichneumon flies which attack and parasitise spiders’ cocoons, piercing them with their ovipositors and laying their eggs inside. The eggs of the Ichneumon fly hatch first and feed upon the eggs of the spider. Two such flies are known to attack the cocoons of the garden-spider, and not a single spider will emerge from a cocoon thus parasitised. The spiders whose cocoons are most subject to these attacks belong, as might perhaps be expected, to the sedentary groups, and the most elaborate but unavailing precautions are often taken to render them Ichneumon-proof. The cocoons of the peripatetic wolf-spiders have never been observed to be parasitised. Even if a spider has survived these early perils there are still many dangers ahead. During its period of growth it has to moult some eight or nine times, and the operation is at least as dangerous as, say, an attack of measles to the human infant. For some time beforehand feeding ceases, and the animal becomes inert and apparently dead, but presently the integument splits, and out struggles the spider, pale and soft, and leaving behind it not only the outer skin but the lining of most of its alimentary canal and of its breathing tubes. Sometimes, as we have said, it fails to extricate itself and dies; quite often it emerges with the loss of a limb, which will reappear—reduced in size—at the next moult. It is necessary to go into retreat for a time after moulting, till strength has returned and the integument has hardened. But the dangers of moulting, though not negligible, are insignificant beside others to which the spider is exposed during its later stages, nor is a prolonged dearth of food necessarily fatal, for, as we have seen, a spider can fast for an astonishing time and yet retain its health if it has a fair supply of water. But there are terrible enemies at hand from which it has little or no protection. Birds, of course, come first, for to most insectivorous birds spiders are acceptable morsels. I have seen a hedge sparrow going conscientiously over a trellis work and picking out all the spiders from the nooks and corners. Then insectivorous mammals make no distinction between the Insecta and the Arachnida, and often eat spiders with avidity, as also will toads and lizards.