April 17, 1950. 
Dr. Roy L. Sexton, 
1801 Eye Street, N.W. 
Washington, D.C. 
l$V 
Dear Roy: 
Herewith some further data on my worms that may be 
of interest to you. The species is usually called the Human 
Bot Fly, Dermatobia hominis (Linnaeus, Jr.) It is a forest 
species ranging from Mexico south to northern Argentina, but 
apparently absent from the West Indies. 
The adult fly is about 12 mm. in length and superficially 
has some resemblance to the ordinary bluebottle fly. The female 
catches mosquitoes and other species of flies, and glues her eggs 
to the abdomen of these insects where they are carried about 
for from 5 to 15 days. The eggs hatch while the carrier is in 
contact with the future host. If the carrier fly is a mosquito or 
other blood sucker it may supply the opening by which the parasitic 
larva enters the skin. If not, it may get in through a hair follicle 
or some place where the skin is moist and sweaty. 
The larva develops in a pocket, opening to the outside. 
Sometimes there is pain connected with its presence and sometimes 
not due probably to location near sensitive nerve dndings, and to 
the individual reaction of the carrier. The larva develops through 
three stages (some Entomologists claim there are four). Larval 
life runs usually from 5 to 10 weeks but may extend over three 
months. The mature larva finally enlarges the opening, drops to the 
ground, and then pupates. In due time an adult fly emerges. 
Ordinarily so long as the larva lives there is no trouble from it, 
except a serous discharge. Sometimes, however, this discharge is 
said to be troublesome. 1 have never seen such a one. 
The larva is best removed by plugging the opening with a 
heavy oil, beeswax, chewing gum or some heavy salve. In due 
