Mag.,’ vol. ix, p. 366). A vast number of non-parasitic insects are injurious to man and beast. Inasmuch as they subsist at the expense of their victims and also adhere to his person during their attacks for a shorter or longer time, they, like the leeches, may be spoken of as free parasites. The leg-sticker (_Stomoxys calcitrans_) penetrates through thick stockings, causing blood to flow freely. The clegg of the West Highlands (_Hæmatopota pluvialis_) also violently attacks man and beast, especially horses. The mosquito (_Culex anxifer_), the gnats (_C. pipiens_, _C. annulatus_, and _C. pulicaris_), and the midge (_Chironomus plumosus_) need only be mentioned. The creeping gnat (_Simulium reptans_) is also very annoying in Sweden. The rôle of the mosquito, as itself constituting a parasite-bearer, will be again referred to in the closing pages of this work (Book II, Section V). The bites of the tsetse (_Glossina morsitans_), though so destructive to the horse, ox, sheep, and dog, are not dangerous to man himself. According to Sir S. Baker, the seroot-fly, or zimb of Bruce, which is a species of _Pangonia_, is excessively annoying to travellers in Abyssinia. Amongst the hemipterous insects the common bug (_Acanthia lectularia_) is sufficiently blood-thirsty; but there is a far more sanguinary species of this kind in South America. This is the pampas benchucha (_Conorhinus nigrovarius_). Our distinguished countryman, Darwin, in his ‘Voyage,’ speaking of these wingless insects, says:--“Before sucking they are quite thin, but afterwards become round and bloated with blood. In less than ten minutes the insect is changed from being as flat as a wafer to a globular form.” This insect somewhat resembles our water-scorpion (_Nepa cinerea_), a non-parasitic species whose bite causes severe pain, as does also the wound inflicted by the water-boatman (_Notonecta glauca_). There are other species of bug, such as the _Acanthia rotundata_ of Réunion Island and _A. ciliata_ of Kasan, the bites of which are worse than that of the common species. The fly-bugs also, such as the _Reduvius personatus_, so common in France, and the _R. amænus_ of Borneo and Java, attack man, although their especial habit is to attack and destroy other insects, including bugs themselves. Other species or varieties of Reduvius (_R. cruentus_, and _R. serratus_) attack man. The last named is an Indian form, capable, it is said, of producing an electric shock.