And now for the sheep who are just as clever really as the wolves. Two of these are caterpillars--quite the most curious pair of caterpillars to be met with in this country--and the third is a sawfly. Sawflies get their name from having an instrument with which they can bore or saw, as the case may be, into leaves or trees, and this is the largest one we have in England. The hunter-insects, as we have seen, disguise themselves so as to get near their victims unawares, and the hunted disguise themselves very often in the same way so as to avoid being seen, but sometimes in such a way that if they _are_ seen they may appear to be much more terrible creatures than they really are. And so we have the sheep in wolves' clothing. [Illustration: THE ICHNEUMON FLY] The hunters of the caterpillars are the ichneumon flies. Ichneumon flies do not eat caterpillars but lay their eggs inside them. They have a special instrument for the purpose, and when the grubs hatch out they gradually eat away the fleshy parts of the caterpillar so that it seldom has strength enough to turn into a chrysalis, let alone a butterfly, or moth, or beetle, as the case may be. Now what is the chief enemy of a fly? Why, of course, a spider. If then something which dreads an ichneumon fly can make itself look like that fly's worst enemy, a spider, it will have a good chance of scoring off the fly. The Caterpillar of the Lobster Moth, of which I show you two pictures, can do this to a nicety. He has, as you see, an extraordinary shape for a caterpillar, I don't think that any other caterpillar in this country has the same long skinny legs--and he is able to strike extraordinary attitudes which make him look very spidery indeed, particularly from in front, for then the two little spikes at the end of his lobster body appear over the top of his head and look like a spider's pincers. Mother Nature has been very careful of her Lobster Moth caterpillar. When he is quite a baby he looks just like a little black ant. When he is asleep he folds up his legs and looks like a shrivelled beech-leaf--he usually feeds on beech--and, when he is attacked by an ichneumon fly (you can make him think he is being attacked by tickling him with a paint-brush) he turns himself at once into a sham spider, by throwing back his head as far as it will go and shuddering his skinny legs in the air. [Illustration: THE PUSS MOTH CATERPILLAR As he looks when angry]