Have you never wondered at the temerity with which certain of these slow-moving, helpless creatures expose themselves to the attacks of their enemies? In a world so full of hungry, winged beings it does seem strange, and when the markings are black and white or some such striking color in contrast with the leaves or bark the temerity seems even more extraordinary, until one learns the simple fact--these creatures are not very good to eat. Not good enough to eat! Supposing that the fly and the mosquito were equipped with some flavor distasteful to the insectivorous birds; if cattle were not good to eat, nor sheep, nor hogs, nor any living, breathing things, what a change there would be in a world like ours! And yet to chemists there is very little difference between some compounds that are good to eat and others that are deadly poison, no greater than that between the poison bitter almond and the sweet one of our dinner table. One cannot help but wonder why it is that when the border-land twixt food and poison is so narrow in the chemistry of the living cell that every creature has not equipped itself with prussic acid enough to preserve itself from its enemies. While this protection holds good against many predaceous creatures, there are various birds and even snakes that have found this particular caterpillar not too bad to eat. [Illustration] A HAIRY SPECTACLE (_Euchætes egle_, Dru.) Many of the caterpillars of our fields are striking in their form and color. This one could easily be seen some distance off and might to birds and others of its enemies be what the skunk is to its enemy the dog--a thing to shun. In the luxuriance of its "plumage" it, in some respects, reminds one of those fantastic forms of fowls produced by close line breeding, the Hudans, for example, or the long-tailed roosters of Japan. Few creatures that we have photographed have been more beautiful than this black and white larva with its hairs in graceful tufts all over its body. What it eats or what its other self is like, I have not yet been able to find out. [Illustration] AN UNKNOWN CATERPILLAR Creatures like this, when they come walking down a garden path, are so striking and so gracefully weird that one would think their forms deserving of more study than they get. There is a reason for this, though, that is not hard to find; they are such transient creatures. A few days in the egg, a week or two as caterpillars, and they pass into their cocoons to emerge as moths or butterflies, and of the two weeks when they are caterpillars, the first part of the time they are too small to make much impression upon us.