[Report 1909] / Medical Officer of Health, Salop / Shropshire County Council.

  • Shropshire Council
Date:
1909
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: [Report 1909] / Medical Officer of Health, Salop / Shropshire County Council. Source: Wellcome Collection.

    68/148 (page 48)
    The chief brecdirg places of the common house-fly are given by Mr. Robert Newstead, Lecturer in Economic Entomology and Parasitology, at the Liverpool School of Tropical Medicine, as “ (i) Stable middens eontainirg feimentirg horse manure or a mixture of this and eow dung ; (2) Middens containing fermenting spent hops ; and (3) Ash])its containing fermenting vegetable matter.” The life history of the fly and particularly the length, of the complete cycle, have a very impor¬ tant bearing upon the measures that should be taken to prevent their multiplication. The length of the cycle varies considerably according to the temperature, but for practical purposes the most important point is the minimum time in which a fly can be produced from a newly laid egg. The number of eggs laid by one fly varies from 120—140. The larva, or maggot, is produced from an egg in eight hours to three or four days ; average 12 hours The transtormation of larva to papa or crysalis takes 5—8 days under favourable conditions ; 6—8 weeks under unfavourable conditions. The fly emerges from the crysalis in 5—7 clays under favourable conditions ; m 14 to 28 days under unfavourable conditions. ■ The whole c5Tle from egg to fly is therefore under the most favourable conditions about 10 to 14 days. In other words, if refuse receptacles are thoroughly emptied once a week they will not act as breeding places for flies. A very important subject that is receiving attention but has not yet been properly worked out is the distance that flies will travel from their breeding places. Upon a correct solution of this problem depend many important matters particularly with regard to the distance that refuse heaps, etc., should be removed from houses. The precautions that should be observed to prevent the spread of disease by flies may be grouped under three headings :— 1. Measures directed to prevent the development of flies by removing their breeding places. 2. Measures to prevent flies coming into contact with matter liable to contain disease germs. 3. Measures to prevent flies coming into contact with food. The measures that are necessary to effect these three objects are more or less obvious. Stable refuse particularly, but also any decomposing animal or vegetable matter are the breeding materials for flies, and in towns more especially stringent measures should be taken to prevent accumulations of this kind for more than a few days. The measures that should be taken to prevent flies coming into contact with dangerous organic matter are broadly speaking, rapid removal of such matter or destruction by fire or burial. To protect food from flies it should be kept in a W'ell ventilated fly-proof cupboard or store. This matter may with profit be considered with respect to the specific measures that should be taken by sanitary authorities in tow'n and country districts.