The medical entomology of Salonica /by Andrew Balfour.

  • Andrew Balfour
Date:
[1916?]
Catalogue details

Licence: Public Domain Mark

Credit: The medical entomology of Salonica /by Andrew Balfour. Source: Wellcome Collection.

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    iy As house flies breed in filth, a certain proportion of them _ actually begin life infected, and a consideration of the adult insect shows how admirably adapted it is for the conveyance of disease germs. I take it you are all familiar with the external anatomy of thes house Wives withers sucking proboscis, its hairy body, its hairier legs with their claws and pulvilli_ or membranous pads which are covered with secreting hairs so that the fly can walk Fig. 5—AZusca domestica. Internal anatomy upside down on the most a./ tongue”: ibe suclkaniss Splhiaryancey. c. cesophagus ; polished of surfaces (Fig. 4). d: proventriculus; e¢. chyle stomach; ff. intestine; h. anus ; x BEANE UN G9 C0 You know also that on its 2 body, wings, legs and feet the fly can and does carry pathogenic bacteria which it may us at the present moment is its internal anatomy, for much of the damage which a fly does is due to its habit of spending the live- long day vomiting and defecating, This is not a pleasant thought, iputat bast tO mbestaccd: Well, the fly has a mouth, a cylindrical tube occupying the first half of the proboscis and passing into the sucking organ or pharynx. From “the latter the- -cesophagus extends backwards, bifurcates and communicates with the crop and with the. proventriculus. ‘The latter runs to the chyle stomach from which springs the intestine, passing on into the rectum which ends in the anus (Fig. 5). Now, before feeding, the fly must imbibe liquid, and its Fig. 6—Fannia canicularis diet, like that of a typhoid case, is Taal ates at fluid. At first this fluid passes into the crop, and when this is distended or, if the fly is disturbed, before distension has occurred, it finds its way into the proventriculus which acts as a kind of mixing tank to prepare an emulsion suitable to the fly’s stomach. After a meal, regurgitation takes place, and the fly spots with which you are familiar are due in part to matter excreted from the anus and in part to vomit. So
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