easily captured when attacking human beings; they alight on their victims with a stealthy silent approach. They appear unable to discriminate between clothing and bare skin as suitable spots for feeding. Amongst a band of mountaineering pedestrians, on a sunny day, it was observable that there would be a dozen or more "blinden breeze-flies" settling on the back of one, whilst the rest of the party were only favoured now and then by one or two apiece. It was apparently the smell of the "home-spun" coat which attracted; the colour of the garment did not seem to be the cause of the selection. Sunshine loving flies prefer white and pale colours. If a dog could speak, he would explain the smell of some "finished" cloth, but, for the sake of the fastidious, the secret is not here disclosed. Very closely allied to the true breeze-flies in habit of life are the species of the genus _Chrysops_, of which two only are often met with in England, namely _Ch. cœcutiens_ and _Ch. relicta_; these flies are very keen blood suckers; they are smaller, slightly more slender and brighter coloured than the commoner _Tabanidæ_; it is characteristic of the genus _Chrysops_ that the antennæ are quite twice the length of the remarkably short horns of the majority of common full-bodied flies; all the species possess beautiful golden glittering eyes (whence the name _Chrysops_), and their wings are spotted and tinted. One of the most horribly disgusting but serious facts connected with flies is observable most conspicuously amongst the wondrous family of the _Œstrida_. These pass the larval stage of life, not on, but inside the bodies of living animals; and the perfect insect, strange to say, is absolutely destitute of a mouth opening. Much misrepresentation has been prevalent, based entirely upon surmise, connecting "myiasis" in mankind, which is various but very rare, with the common infliction of horses and horned cattle with _Œstrid_ maggots. Myiasis is the medical term given to all the various forms of animal infliction by internal parasitic maggots, and this subject is reserved for discussion in the next chapter. The characteristics and natures of the very numerous tribes and families of other kinds of flies will be found summarised in the Appendix of this booklet. CHAPTER IV MYIASIS AND THE _ŒSTRIDÆ_