Ticks, as they affect the soldier, may be divided into two families. The first of these, the Argasidae, are usually associated with human dwellings, fowl-houses, dove-cotes, and so on, and are more commonly parasitic on fowls than on cattle or human beings. The members of this group hide away in crevices and corners during the day, and come out at night to feed, for ‘their deeds are evil.’
Fig. 42.—Ixodes ricinus. Mouth-parts of the female: A, seen from the dorsal, B, from the ventral surface. The median, dotted, portion of the left-hand figure is the sheath; the toothed portion the hypostome. The lateral process is the pedipalp shown only on one side. × 35. (After Nuttall and Warburton.)
Argas persicus, known to travellers as the ‘teigne de miana,’ is of an oval form, of brownish-red colour. The male measures 4 mm. to 5 mm. in length by 3 mm. in breadth; the female 7 mm. to 10 mm. in length by 5 mm. to 6 mm. in breadth. This creature frequents the northern parts of Persia, and occurs in many other warm countries. In South Africa it is known as the ‘tampan’ and ‘wandlius,’ where it is mainly a fowl-parasite. In Persia it is very much dreaded, though probably the effects of its bite are due to the unsuitable treatment the punctured skin receives and the consequent invasion of the tissues by septic bacteria. In South Africa it is frequently fatal to fowls, especially to chickens; but the death is there believed to be due to the loss of blood. It is definitely proved to convey Spirochaetosis.
We have not yet explained that ticks pass through several stages as they advance from the egg to the adult. The larval stage of A. persicus will remain on its host for five days. It then leaves, and moults in retirement. After the moulting it visits its host by night and remains on it for about an hour. This second stage, known as the ‘nymph’ stage, moults twice, and the female in each stage becomes much distended with blood—‘gorged,’ as the saying is. With each moult it becomes larger, but otherwise does not alter much in appearance. The adult female also, like the nymph, visits the host from time to time, and between these visits deposits eggs in great quantities in sheltered crevices—some 50 to 100 being deposited at once.
Fig. 43.—Argas reflexus, female. On the left the dorsal view of a specimen laying eggs; on the right a ventral view of the same. (After Brumpt.)
Argas reflexus, the ‘marginated tick,’ is yellow and white—the Papal colours. It is common near dove-cotes and pigeon-houses, and often attacks people sleeping in their neighbourhood. Its bite causes much irritation, and sometimes leads to vesicles and ulcers. At one time it was very common in Canterbury Cathedral, and so worried the worshippers that it took all the eloquence of the ‘Very Reverend the Dean’ to overcome its repellent powers.
Fig. 44.—Ornithodorus moubata, an unfed female. To the left a ventral, to the right a dorsal view, showing the crinkled skin. (After Brumpt.)