The Bornean jungles are full of life, and of the sounds of life, which are more marked in the early mornings and in the evenings. Birds are plentiful (there are some 800 species), some of beautiful plumage, but few are songsters. Insect life is very largely represented, and includes many varieties of the curious stick and leaf insects,[11] hardly to be distinguished from the twigs and leaves they mimic. Also the noisy and never tiring cicadas, whose evening concerts are almost deafening, and frogs and grasshoppers who help to swell the din. There are many varieties of beautiful butterflies, but these are to be found more in the open clearings. Though there are no dangerous animals, there are many pests, the worst being the leeches, of which there are three kinds, two that lurk in the grass and bushes, the other being aquatic—the horse-leech. Mosquitoes, stinging flies, and ants are common, and the scorpion and centipede are there as well. Snakes, though numerous, are rarely seen, for they swiftly and silently retire on the approach of man, and one variety only, the hamadryad, the great cobra or snake-eating snake, is said to be aggressive. The varieties of land and water snakes are many, there being some 120 different species. Natives often fall victims to snake bites. Pythons attain a length of over twenty feet;[12] they seldom attack man, though instances have been known of people having been killed by these reptiles, and the following story, taken from the _Sarawak Gazette_, will show how dangerous they can be. At a little village a man and his small son were asleep together. In the middle of the night the child shrieked out that he was being taken by a crocodile, and the father, to his horror, found that a snake had closed its jaws on the boy's head. With his hands he prised the reptile's jaws open and released his son; but in his turn he had to be rescued by some neighbours, for the python had wound itself around his body. Neither was much hurt.