. Entomology for medical officers. Insect pests; Insects as carriers of disease. ORDER SIPHONAPTERA (APHANIPTERA): FLEAS 193 abdomen. The curved receptaculum seniinis is a conspicuous object in the female when the animal is mounted as a transparent object. The eggs are large and are dropped by the female casually (?>., are not attached to the residential host of the parent). They fall to the ground and may be found in the places where domestic animals sleep. In summer the eggs hatch in two, three, or four days, but in winter the develop- ment within the egg may be prolonged to nearly a fort
. Entomology for medical officers. Insect pests; Insects as carriers of disease. ORDER SIPHONAPTERA (APHANIPTERA): FLEAS 193 abdomen. The curved receptaculum seniinis is a conspicuous object in the female when the animal is mounted as a transparent object. The eggs are large and are dropped by the female casually (?>., are not attached to the residential host of the parent). They fall to the ground and may be found in the places where domestic animals sleep. In summer the eggs hatch in two, three, or four days, but in winter the develop- ment within the egg may be prolonged to nearly a fortnight. The larva (Fig. 75) is an active, footless maggot, of a whitish colour, and is sparsely but regularly hairy. It is composed of a head and 13 segments of nearly uniform diameter, the last segment ending in a pair of hooks. The head carries a pair of small antenna, a pair of stout serrated jaws, and a pair of maxillae with jointed nerve corcT -ant. Fio. 75.—Larva of Bat-flea ^Cerate The larva eats the organic matter contained in the dust in which it lives, and in summer is full grown within a fortnight, though in winter growth is much delayed. When full grown the larva spins a cocoon, in which it pupates. The cocoon is generally coated with adherent dust, and the pupa inside it is a small humpbacked creature faintly resembling the adult. The duration of the pupal stage depends upon the temperature, the usual term in warm weather being about a fortnight. Classification.—The number of species of fleas already known is considerable. Mr C. F. Baker, in his incomplete revision of the order, gives a list of 135 species, and expresses the opinion that many hundreds of species will eventually be found. Our only concern here is with the limited number that have been found upon the rats and mice that frequent human dwellings, and with those few that attack man. These belong to two families, the Pulicidce and the Sarcopsyllidce. N. Please note that these images are extrac
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