Health Notes.
Fly Danger.

With the approach of summer and its seasonal diseases a few remarks concerning that human enemy and carrier of many infectious diseases, the common house fiy (musca domestica) will not be out of place.

First of all, remember that the four commonest means of carrying infection are flies, fingers, food and faeces, but of the four the fly is the greatest menace of them all.

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Take the life history of the fly and its various stages of development. First there is the ovum or egg which develops in from 8 to 24 hours. A single fly lays from 100 to 150 eggs at a time and does this five or six times in a season. Then comes the larval or maggot stage which takes from four to eight days. Then the pupa or chrysalis stage varying from three to five days ending in the fully developed fly. The duration of the different stages varies according to the temperature being much shorter in a hot climate than in a dry one.

In selecting a site for the laying of the eggs, the fly prefers a medium which will provide both heat for development and food for the maggot, the ideal being decaying vegetable matter about to ferment, such as kitchen refuse or stable offal.

In structure the fly has a proboscis, salivary glands, a large crop which holds food laden with germs, and a stomach. Now the salivary glands are the only digestive glands and can deal only with the starches and sugars, therefore it must get its proteid foods in a pre-digested form. The former it gets from the dining table and the latter from refuse, offal, latrines and stable debris.

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Now you will understand the chain of infection from filth to the food on the dining table, the sugar basin, milk jug, bread and other foods left exposed. Not only do the feet carry the infection, but also the liquid in the crop which the fly ejects to moisten dry foods such as sugar and bread is laden with germs of disease. Unfortunately, the fly has but few natural enemies and therefore it falls upon all to exert every effort in its destruction.

Firstly, we must see that we do not provide suitable breeding ground and must deal with our rubbish in such a way that it is not left exposed. Burn what can be burnt, wrap up in paper what has to be put in the dust bin, and bury deeply whatever cannot be disposed of otherwise. Make free use of the various contrivances for the destruction of the fly, such as tanglefoot,