. The Acarina or mites. A review of the group for the use of economic entomologists. Mites. fWm\^ Fig. 230.—Beak of Histiostoma americana. (Author's illus- tration.) Fig. 231.—Leg I, and tip of mandible of Histio- stoma americana. (Author's illustration.) plate of sucking disks. They are fitted for clinging to the hairs of small mammals, and for this piu-pose there is a longitudinal groove on the ventral plate, ajid each side of the groove a broad, raised, striated surface that may be pressed against a hair lying in the groove. In the early days of acarology the relation of the hypopus was unk
. The Acarina or mites. A review of the group for the use of economic entomologists. Mites. fWm\^ Fig. 230.—Beak of Histiostoma americana. (Author's illus- tration.) Fig. 231.—Leg I, and tip of mandible of Histio- stoma americana. (Author's illustration.) plate of sucking disks. They are fitted for clinging to the hairs of small mammals, and for this piu-pose there is a longitudinal groove on the ventral plate, ajid each side of the groove a broad, raised, striated surface that may be pressed against a hair lying in the groove. In the early days of acarology the relation of the hypopus was unknown, and Hypopus stood for a separate genus, allied more to Gamasus than to Tyroglyphus. The history of the discovery of its relationship is replete with interesting details. Duges in 1834 wondered if Hypopus was not a larva. In 1844 Gerv^ais placed Hypopus as a section or subgenus of Tyroglyphus, but not doubting they were mature creatures. Dujardin in 1847, after a close examina- tion of the mite, decided that Hypopus was an immature migratorial form of Gama- sus. In 1868 Claparede bred various tyro- glyphids and noticed that certain nymphs when they transformed did not produce the adult Tyroglyphus, but a Hypopus. His observations were correct, but his con- clusion that Hypopus was the male of Tyroglyphus was erroneous. About the same time Robin and Fumose published a paper' in which they described the true male of Tyroglyphus, thus showing that Hypopus was not the male Tyroglyphus. In 1873 Megnin published a famous work on the life history of Tyroglyphus rostro-. (Author's Fig. 232.—Ghjciphagus obesus. illustration.) serratus Megnin, in which he proved that Hypopus was a nymphal form oi Tyro- glyphus, due, he supposed, to the dryness of the atmosphere or the lack of food. Murray in 1876, in investigating the subject, came to the conclusion that Hypopus was a ferocious parasite which devoured the entire internal anatomy of its victim and then left the cast skin in sea
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