It may be objected that, if open dust-bins are used, house-flies after visiting the same may return to the house and subsequently contaminate food in the larder. There will be such a possibility, but the danger thereof can be minimised, and would in fact be nearly automatically cured, as prospective fly progeny perished. Furthermore, there are circumstances which indicate that the said danger would not be great, and anyhow nothing comparable to the baneful effects which are now endured. The worst germs are not those of newly discarded food remnants; the commonest and well-known bad smelling germ of ordinarily "tainted" meat, which is exceptionally attractive to the house-fly and the blue-bottle, is fortunately, after cooking, not so dangerous as some of those other deleterious micro-organisms mentioned in the last chapter. Taking one thing with another the balance of benefits and disadvantages will incline overwhelmingly in favour of open dust-bins, wherein food remnants may purposely become fly-blown. An improved dust-bin lid has been contrived which combines with the cover a centrally held wire-gauze "balloon" fly-trap, wherein flies will congregate and be imprisoned when attempting to leave. Unfortunately air-tight dust-bins have been very generally recommended as a grand device of hygienic value; hence it is most necessary that unthinking people at large should be informed how much better it is to use open bins which can catch and secure for destruction prospective fly-broods. It may be asked—why not trap and kill the breeding females? The reply is that to do so will be good, as is to be explained in the next chapter; but contrivances for the latter procedure are apt to be less effectively put into general operation. The fly swarms of mews, arising from accumulations of stable manure, will be difficult to alleviate without stringently enforced measures, but it is a mistaken notion to believe that town flies are bred in stables to such an extent that the invaders of our dwellings and town restaurants, shops, and markets, are merely or mainly the overflow of the mews. The concentration of many kinds of flies is very dense around ill-kept mews, and in midsummer-time a large percentage will be true house-flies. Frequent removal and cremation of stable manure would be quite effectual, but there is reason to think that, if proper care be taken, no such drastic procedure as cremation will be absolutely necessary, unless perhaps for the months of July and August.