One of the most beautiful examples of mimicry was discovered by Gerstäcker, not in free nature, but in the entomological collection at Berlin. There he found beside a green, metallic weevil-beetle, one of the Pachyrhynchidæ from the Philippines, two other insects with the same metallic sheen and very similar form of body. They had been put in beside the weevil as duplicates, but more careful observation showed that they were delicate Gryllidæ, which mimicked the hard beetles so deceptively that even the practised eye of the entomologist was misled by them. Later on it was shown that these Gryllids live in the Philippines beside the weevils, and even on the same leaves with them, and that the beetles are protected from the attacks of birds and other enemies by the extraordinary hardness of their cuticle. The case is especially remarkable because in general the Gryllidæ have no metallic shimmer, and the form of body must have been considerably altered to make them resemble the beetle. The usually broad head of the Gryllids is in this case narrower, the usually flat wing-covers are arched and pear-shaped, and the legs have become quite beetle-like. The security enjoyed by the weevil must be very perfect, for it is mimicked by three other species of beetle in the Philippines. Animals can also be protected from attack by the possession of dangerous weapons. To this class belong insects with poisonous stings, like the bees, wasps, and ants, and in some degree also the ichneumon-flies. We cannot wonder, therefore, that these dreaded species find imitators. In this case it is not of so much importance that the copy should be rarer than the model, for anything that looks like a dangerous insect will be avoided, since close investigation is in this case attended with danger. So we find that hornets, wasps, and bees are frequently imitated by other insects, by beetles, flies, and butterflies; and these must derive a certain advantage, even when the resemblance is only a general one. Many Longicorns, which visit flowers, are striped black and yellow, like a wasp, and so are many flies, like the species of _Syrphus_, and so on. The Longicorn _Necydalis major_ bears a strong resemblance to a large ichneumon-fly; it has the same long-drawn-out body, the same swellings on the femur and tibia, the curved antennæ, the glossy brown colour, and its wing-covers are quite short, leaving the wings free, so that the deception is very complete.