About 1900, Blanchard observed the presence of packets of large-sized eggs under the abdomen of certain mosquitoes from Central America; and in 1910, Dr. Moralès, of Costa Rica, declared that the Dermatobia deposited its eggs directly under the abdomen of the mosquito and that they were thus carried to vertebrates. Dr. Nunez Tovar observed the mosquito carriers of the eggs and placing larvæ from this source on animals, produced typical tumors and reared the adult flies. It remained for Surcouf (1913) to work out the full details. He found that the Dermatobia deposits its eggs in packets covered by a very viscid substance, on leaves. These become attached to mosquitoes of the species Janthinosoma lutzi ([fig. 84]) which walk over the leaves. The eggs which adhere to the abdomen, remain attached and are thus transported. The embryo develops, but the young larva ([fig. 82]) remains in the egg until it has opportunity to drop upon a vertebrate fed upon by the mosquito.
Muscidæ
The following Muscidæ, characterized elsewhere, deserve special mention under our present grouping of parasitic species. Other important species will be considered as facultative parasites.
Stomoxys calcitrans, the stable-fly, or the biting house-fly, is often confused with Musca domestica and therefore is discussed especially in our consideration of the latter species as an accidental carrier of disease. Its possible relation to the spread of infantile paralysis is also considered later.
The tsetse flies, belonging to the genus Glossina, are African species of blood-sucking Muscidæ which have attracted much attention because of their rôle in transmitting various trypanosome diseases of man and animals. They are characterized in Chapter XII and are also discussed in connection with the diseases which they convey.