452 MOSQUITOES 



cones of Caracas, the mosquito is utilized by the Dermatobia fly 

 as an aeroplane for transporting her eggs or larvae to a suitable 

 host for development, and we would have here, if true, one of 

 the strangest interrelations of animals in the whole realm of 

 nature, comparable, perhaps, with the manner in which certain 

 mites of the family Tyroglyphidae assume a special traveling garb 

 and adhere to the appendages of flies to obtain transportation 

 to new feeding grounds (see pp. 339-340) . 



Dr. Neiva, of the Institute Oswaldo Cruz, at first did not 

 believe in the mosquito theory. He pointed out that in various 

 parts of tropical America not only mosquitoes, but also craneflies, 

 ichneumon-flies, certain large hairy flies and other insects are 

 accused of being Dermatobia carriers, though they could not 

 possibly serve in this capacity. It is known now, however, that 

 various species of flies as well as the mosquitoes are used by 

 Dermatobia, and it would be expected that at times a fly, impelled 

 by the urgent desire to oviposit, might be content to deposit her 

 eggs on insects which could not very well serve the purpose of 

 transporting the eggs to a suitable host. Neiva, when he ob- 

 jected to the mosquito theory, had not found any egg-carrying 

 mosquitoes in Brazil, where Dermatobia is common, but in a later 

 publication he records not only Janthinosoma lutzi, the mosquito 

 incriminated in Venezuela and Central America, as an egg-carrier, 

 but also another species of Janthinosoma, J. posticata, and several 

 kinds of muscid flies (see p. 514). He also found on dissection of 

 female Dermatobia flies, that the eggs were in various stages of 

 development and thought this argued against the utilization of 

 mosquitoes as carriers, but it has subsequently been shown by 

 Neiva himself that the eggs are laid in small groups on captured 

 insects, and by no means all at one time. Dermatobia is fre- 

 quently found pestering cattle and horses, and egg-containing 

 females sometimes persistently follow human beings. It is not 

 certain that the fly does not sometimes deposit its eggs directly 

 on the skin of the host in which the larvae are to develop, but its 

 presence near large animals may be due to its pursuit of other 

 insects which swarm around them. 



There is no doubt any longer but that the widespread popular 

 belief in the part played by the mosquito is founded on fact. 

 Insects carrying eggs of the fly have repeatedly been found, and 



