Those Who Help 191 



hominis, apparently does not lay its eggs directly on its 

 host but captures other flies, usually of the genus Limno- 

 phora, or mosquitoes, and lays its eggs upon them, releas- 

 ing them immediately. These then hght upon man or beast 

 and the egg, adhering to the skin of the host, hatches at 

 once and the larva quickly dives beneath the hide of its 

 victim. The most complete account has been given by my 

 friend Lawrence Dunn, a medical entomologist in the 

 Gorgas Memorial Laboratory in Panama. Seated at the 

 edge of a small stream near Summit in October 1929, he 

 was infested by six of these larvae, two on each forearm 

 and two on his right leg. He recognized at once that here 

 was an opportunity to study the emergence of these crea- 

 tures in great detail. He returned to the laboratory and in 

 spite of the most exquisite torture and the revolting fetid 

 discharge from the wounds as the larvae increased in size, 

 he patiently waited no less than fifty days until the crea- 

 tures finally emerged. They weighed each about 0.725 

 gram and were each about 2 5 millimeters long and 1 1 mil- 

 limeters in diameter. His account of the final stages is 

 worth quoting, for while innumerable travelers have suf- 

 fered from these beasts, never before has the exact time 

 between the laying of the egg and the emergence of the 

 larva been made known. After they dropped from his skin 

 Dunn placed these larva in damp sand and twenty-five 

 days later the adult flies appeared. 



Brooks and I never were infested more than a few days 

 before we got rid of the beasts. Dunn's incredible patience 

 and penetrating observations mark him as a pioneer with 

 the spirit of a born investigator. 



