THE SCREW-WORM. 
535 
In “ Animal Parasites and Messmates,” by Van Benenden, 
page 119, there appears the following: “There is another fly 
in Mexico which is dangerous to man; it is known by the 
name of Musca hominivora , or more correctly, Lucilia liomini- 
vora. Vercammer, a military surgeon of the Belgian army, 
relates that a soldier in Mexico had his glottis destroyed, and 
the sides of the roof of his mouth rendered ragged and torn, 
as if a cutting-punch had been driven into those organs. This 
soldier threw up with his spittle more than two hundred larvas 
of this fly.” 
Prof. James Law, of Cornell University, in a letter to the 
writer, said: “Under the name of Lucilia hominivora it is said 
to be very destructive to the French convicts at Cayenne, the 
fly depositing its eggs in the mouth and nostrils during sleep.’ 
No cases in man have fallen under the personal observa¬ 
tion of the writer. 
The fly seems to be well distributed over the American 
Continent, for Dr. Williston, of Yale College, writes that “it 
occurs everywhere from Canada to Patagonia.” Although so 
generally distributed, only in Texas does it bear an economic 
importance in the United States. Of all our domesticated 
animals cattle suffer the most from its ravages. They occur 
in wounds from horns, castrating, spaying, branding, dehorn¬ 
ing, barbed wire injuries, and often where ticks have burst on 
the brisket, flank, or just behind the udder of cows. They 
often occur in the vulvas of fresh cows, especially if there has 
been a retention of the placenta or afterbirth. Young calves 
are almost invariably affected in the navel and often in the 
mouth, causing the teeth to fall out. One case occurred in 
the first stomach (paunch or rumen) that is worthy of men¬ 
tion: Last September the writer had occasion to kill a Jersey 
bull calf, probably two months old, that had screw-worms in 
both hind legs just above the hock joint. On opening the 
abdomen I found hair-balls in the stomach (rumen), and, to 
my surprise, about twenty-five fully matured screw-worms 
almost buried in the wall of that organ. I placed some of the 
worms in moist earth, and in ten to twelve days they hatched 
out genuine screw-worm flies. How did they come there ? 
