. Des parasites animaux et la maladie humaine. Parasitologie médicale ; insectes en tant que porteurs de la maladie. 338 Les mites jusqu'à ce qu'ils ont pleinement mis au point les hommes et les femmes. En conséquence son abdomen distendu énormément devient de sorte que le reste de l'organisme apparaît comme seulement un tout petit accessoire à un côté d'elle. Une femelle gravide (Fig. 139) complètement distendu peut atteindre un diamètre de 1,5 mm. (-JV de pouce) alors que normalement elle ne mesure que 0,2 mm. (J^s de pouce) de longueur. Dans les conditions les plus favorables que six jours peut s'écouler entre le moment où les jeunes femmes sortent de la mère avant qu'ils procréer

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. Animal parasites and human disease. Medical parasitology; Insects as carriers of disease. 338 THE MITES until they have become fully developed males and females. Her abdomen in consequence becomes enormously distended so that the rest of the body appears as only a tiny appendage at one side of it. A gravid female (Fig. 139) fully distended may reach a diameter of 1.5 mm. (-jV of an inch) whereas normally she measures only 0.2 mm. (j^s of an inch) in length. Under the most favorable conditions only six days may elapse from the time the young females emerge from the mother before they reproduce a brood of their own. The brood varies in number from a few dozen to over 200. Like many other beneficial things, these predaceous little mites may become a distinct nuisance, and many serious outbreaks of infestation of human beings by them are on record, especially among the grain threshers of the central portion of the United States and among laborers who handle stored grains and other dry foods. In our Middle West their attacks have often been attributed to harvest mites. In Italy the rash produced by louse-mites is called " miller's itch." Several outbreaks have occurred in the United States due to the use of new straw mat- tresses. The transformation of all the grain-moth caterpillars into moths leaves the mites with their normal food supply cut oif, and they are then ready to feed upon any flesh to which they may have access in an effort to prevent starving to death. The itching rash produced begins about 12 to 16 hours after exposiu"e to the mites. At first they produce pale hivelike spots, which later become red and inflamed, and itch unbearably. Little blisters, the size of a pinhead or larger, appear at the sites of the bites and these later develop into little pustules. Scratch- ing results in the formation of scabs, and when these fall off dark spots which are slow to fade are left on the skin. The rash and itching normally disappear within a week

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