Fig. 409.—Ochromyia larva on the skin of man, South Africa. 3/1. (After Blanchard.)
Ochromyia anthropophaga, E. Blanch.; Cordylobia arthrophaga, Grünberg.
Indigenous to the Senegal and neighbouring districts; in the district of Cayor (between the mouth of the Senegal and Cape Verde) the larva is known as the “ver de Cayor.” It lives under the skin, especially at the lower extremities and the lower region of the trunk, producing small boils, which cause pain, but after about eight days, when the larva leaves the body to enter the pupal stage, the pain discontinues. Besides man the larva occurs in dogs, goats, cats, and in the jackal. It is still questionable whether the fly deposits its eggs direct or on the ground, from whence the larvæ as they emerge gain access to animals and man. Larvæ yellowish-white, 14 mm. long, 4 mm. wide, eleven segments[414]; head with two globular antennæ-like appendages, two black curved mouth hooks, and two wart-shaped, finely spinous structures at their base. Body evenly covered to the seventh segment with small black prickles, which are stronger at the sides and the anterior borders of the segments; from the seventh they increase in size, on the two hindermost they are wanting; on the last segment two deep yellow spiracles, each with three markedly curved fissures; in addition two stigmata on the posterior border of the first segment. Duration of the larval stage about eight days. Upon the construction of roads in Guinea the larva is spread by dogs far into the interior.
Auchmeromyia (Bengalia) depressa (Walker).[415]
Fig. 410.—Head end of “larva of Natal.” Magnified. (After Gedoelst.)
Distributed in the region of Natal and apparently over the whole of South Africa. The “larva of Natal,” as one may still term the species provisionally, as its identity is not certain, possesses on its head (besides the mouth hooks) lateral protuberances beset with a row of chitinous spines. The cuticle of the body is spinose. The spines are difficult to recognize on account of their transparency and want of colour; they are longest over the anterior segments, from the fifth they become smaller, and over the hindermost they are very small. Apart from the foremost segment, the position they take is that of rows running transversely or obliquely, two to four generally in juxtaposition; the number of spines in the groups gradually increases posteriorly, attaining the number of eight to twelve on the sixth segment, and this number is maintained to the end of the body. Isolated spines are found over the head; over the second, third and fourth segments single ones are still found adjoining the groups of spines, from the fifth onward they are wanting. From here the spines cover the whole free surface of the segments; over the fourth the anterior three-quarters, over the third two-thirds and over the first and second only the anterior half. The stigmata found at the anterior end also serve as distinguishing characters. The parasitic stage appears to last about fourteen days. [Fuller (Agric. Journ., Dept. Agric. and Mines, Natal, 1901, iv, p. 606) refers to this as Bengalia depressa also.—F. V. T.]
Genus. Cordylobia, Grünberg, 1903.
Cordylobia grünbergi, Dönitz.