MOSQUITOES AND DERMATOBIA 451 



parasite is passed is less perfectly immune to the parasite, and 

 the parasite less perfectly adapted to the host, than is the case 

 between a parasite and the host in which it goes through the 

 mature sexual phase of its life history. In the case in hand 

 man may be looked upon as the disseminator of a deadly disease 

 among mosquitoes in much the same way that the mosquito 

 may be considered the disseminator of deadly human diseases 

 in the case of malaria and yellow fever. 



Mosquitoes and Dermatobia 



In many parts of tropical America where the man-infesting 

 botfly, Dermatobia hominis (see Chap. XXVII, pp. 513-515), is 

 found there has long been a belief among the natives that the 

 maggots of this fly, which develop under the skin of man and of 

 many other animals, are in some way the result of mosquito bites. 

 Inhabitants of some endemic regions, e.g., Trinidad, point to 

 mosquitoes as the cause of the skin maggots, and in some places 

 the larvae are known as " mosquito- worms." Until recently 

 the scientific world looked upon these beliefs as mere superstition, 

 and gave them no further thought. In 1911, however, Dr. 

 Morales, of Guatemala, received a specimen of a mosquito sent 

 him as a mosquito " carrier " of Dermatobia, with eight relatively 

 large elliptical eggs glued by their posterior ends to its abdomen. 

 A few days later a larva emerged from one of the eggs, and was 

 induced to enter an abrasion in the skin of an attendant, where 

 it thrived so well that for the patient's sake it was removed after 

 a little over six weeks and transplanted to the back of a rabbit. 

 Here it continued its development and escaped, probably just 

 before pupation, exactly two months after the eggs were first 

 received. Dr. Morales was quite certain that the larva was 

 really a Dermatobia. In the same year Dr. Tovar of Caracas, 

 Venezuela, made similar discoveries, and is said to have caused 

 typical Dermatobia tumors by allowing an egg-laden mosquito 

 to bite a susceptible animal. From these tumors the larvse 

 were obtained at the end of 11 days and from these larvse the 

 adult flies were reared. Dr. Surcouf of Paris, Dr. Knab of the 

 United States, and Dr. Sambon of England have published ob- 

 servations of their own bearing on the r61e of the mosquito in 

 transmitting Dermatobia infection. From these observations 

 one would be inclined to believe that, as expressed by Dr. Rin- 



