Farmyards and the scattered dwellings of rural districts remain to be considered, and no doubt herein the difficulty is great, but not hopeless. The latter will be persuaded to follow suit when the good effects of town and suburban policy become apparent.
Something more than usual is desirable for the protection of cattle from the breeze and the œstrid flies at midsummer. The latter, at all events, could be easily exterminated by giving butterfly nets and encouragement to children, who would enjoy the fun. Although the close approach of strangers may alarm grazing animals, after the latter have galloped away a very good chance will occur of capturing the slow flying gravid female worble-fly with a butterfly net, or of felling her to the ground with a suitable instrument; if missed on the first attempt, other chances can be got again and again by waiting until the said same fly has returned to threaten her intended victims. The writer has often succeeded in felling the slow flying gravid female worble-fly with a mere walking stick. It is strange that no farmers' entomological friend has hitherto suggested so common-sense a remedy as butterfly nets, which should be of a dark green colour. A company of our popular boy scouts, marching in a skirmishing line on an August Bank Holiday (or a preceding Saturday), over ground where grazing animals are observed showing behaviour conspicuously indicative of attacks by œstrid flies, would enjoy doing grandly useful execution. Every capture should be substantially rewarded.
In an organised campaign of house-fly extermination it may rather be expected that the principal trouble will be with the stable men of unsanitary mews. In the United States of America very stringent bye-laws have been made and enforced. Some of these, perhaps, deserve consideration for adoption, with judicious improvements, in England, but the policy of the OPEN DUST-BIN and CREMATION raises new hopes of success far beyond any advantages hitherto obtained in America.
CHAPTER XI
CONTROL WITHIN THE HOUSE
Many minor plans have been proposed for obviating or alleviating the perils and plague of invading fly swarms; several such plans may be well carried out on a private domestic scale, but one cannot expect any of them to be adopted universally. In domestic methods people will prefer some one plan, some another, whilst some will not personally aid in the work of fly destruction in any single way perseveringly. This latter circumstance emphasises the necessity of a dominant control by local authority for the safeguarding of all inhabitants, including the delinquents themselves in spite of themselves.
The plan, as detailed in the last chapter, of enticing breeding females to lay their eggs within depositories of discarded food remnants and garbage, can be practised on a smaller scale with great advantage everywhere. Kitchen refuse of many kinds, not neglecting potato and turnip parings, cabbage leaves, or even tea leaves, should all be collected in brown paper bags, which should be left open for a few days in suitable places round about the house for the free access of gravid female house-flies. Every such collection should he cremated on the third day. In a paper, read at a recent congress of the Royal Sanitary Institute, on "Destruction and Prevention of Household Pests," Dr. Gay advised rich and poor, in every household, whether or not a sanitary dust-bin was in use, instantly to wrap up in paper all such fly-breeding materials in readiness for cremation. However, to do so would be missing the much more effectual course of applying my "egg-trap" plan of collections in exposed open bags for cremation on the third day.
For indoor use insecticide methods are more suited; and the best of these are immensely more effective than some popular devices, which make a remarkable display and sell well, but which the purchasers soon become neglectful to keep in constant use. Traps in the form of wire-gauze cages, and glass non-return bottles belong to this latter class of contrivances; when seen crowded with struggling victims, the employment of such articles captivates many observers; but their real efficiency will be found to fall far short of general expectation. The explanation will be apparent when the use of the wire-cage trap is contrasted with the success of a good fly poison. Given, say, a dwelling room on a midsummer day containing ten female flies and ten idle dancing male flies; in such cases not more than half the females and one quarter of the males will get imprisoned within four or five hours by the employment of the wire-cage trap, but with a good method of setting poison nine-tenths of the females and half the males may be killed within the same period. In the case of poisoning, the dead have to be swept up, whilst fly traps have the advantage of collecting the victims; but, unless the inmates are carefully destroyed, a few will manage sometimes to escape from the traps, especially as side window light changes and daylight fades. In these fly traps it is only the perseverance of the prisoners in struggling towards outer light which prevents their exit by the entrance aperture.
Stickfast adhesive papers and suspended tapes and strings look very effective when seen crowded with accumulated captures; but, again, these "exhibition" appearances are as deceptive in suggestions of real efficiency as are the crowded cage traps last mentioned; moreover, sticky messes are not commendable or convenient articles for placing where most wanted. Truly, suspensory strings are attractive resting resorts for dancing males, but the worst agents of Beelzebub are the females, which have a keener appetite for food and for pestering humanity.
There remain for consideration insecticide poisons. A great choice of materials can be supplied by the chemist's shop, and various methods of using them have been recommended. In old times country people prepared decoctions of Amanita muscaria, the fly toadstool, a large orange-scarlet, or crimson, mushroom-shaped fungus commonly appearing in autumn in woods where birch trees abound. Strange to say, such decoction will poison flies of many kinds, although they, and many different creatures, feed with impunity on other fungi which are more deadly poisonous to mankind.