If we can find a swiftly running stream within easy reach a little time may be spent in searching the submerged rocks and plants for the miniature stages of the buffalo gnat. This insect, which is known to scientists as _Simulium_, has a most interesting life history. Its popular name is derived from its hump-backed appearance and its supposed resemblance to a buffalo. The female lays her eggs on a rock or reed, just covered by running water, she never lays them in still water. The greenish-brown, club-shaped grubs which come from the eggs are curious and they will repay examination under a low magnification. At the more blunt end of the creature there is a large sucker; it uses this as a foot to support itself in an upright position. If we examine our specimen under water we shall see that its horny head is decorated with a pair of fans, each one composed of about fifty threads. These fans open and close with a rhythmic movement and, in doing so, attract small floating water plants to the mouth. Just below the head there is a single leg with a sucker foot. When the grub walks, it does so by a looping movement, holding fast to its support with fore and hind suckers alternately. The next stage in the life of the young buffalo gnat is even more curious. On the surface of some submerged leaf we shall probably be able to find a number of the slipper-shaped pockets made of closely woven silk, in which the insect spends the final portion of its life before turning into the perfect fly. Within some of the pockets we shall find the creature itself and it must be studied. Its head is still ornamented with a pair of fans, but in this case they are gills by means of which the insect breathes and not food scoops, for it has reached a stage when food is not taken. On its tail end there is a hook, by means of which it anchors itself to its slipper-shaped pocket. Probably we shall find bubbles of air collecting round some of the insects, within their pockets; as the time approaches nearer and nearer for the change to the perfect insect to take place the bubbles grow larger and larger. Eventually the fly emerges within a bubble, shakes it free from the pocket and floats to the surface of the water without wetting its wings. The pond will supply insects quite as interesting as the running stream. Here we may find the eggs of Caddis flies, enclosed in jelly-like envelopes, rope-like, horse-shoe shaped or simple masses. The caterpillar cases of these insects should be slightly magnified and examined, for they are marvellously constructed of shells or sand, pieces of stick, leaves or other vegetation.