DIPTERA. 91 
If we take the estimates as a whole, some of which have been pub- 
lished since the first writing of this chapter, it is evidently a modest 
estimate to consider the losses from the different sources of injury to 
hides, loss in milk and beef, and lessened vitality to be $2.50 per head of 
cattle for the whole United States, making a grand total of $90,000,000 
on the basis of the census of 1880. Were this loss something unavoid- 
able or requiring the expenditure of much time or money to prevent, 
there might be some excuse for its continuance, but since it can by 
simple and inexpensive methods be not only wholly prevented from 
year to year, but practically exterminated from the country, thereby 
avoiding both the loss and the trouble of applying remedies in the 
future, it would seem of the greatest utility to adopt those necessary 
measures without further delay. The preventive measures necessary 
become at once apparent by knowledge of the life history and habits of 
the insect. 
OCCURRENCE OF WARBLES IN MAN. 
There are many instances of the occurrence of the warble in man, and 
these records contain instances which are to be referred to both of the 
species, Dr. Riley having positively identified one such case at least 
for lineata, and Dr. William Schoyen being authority for the European 
records of bovis. In all these cases there seems to have been a large 
amount of migration on the part of the larva and usually an emergence 
from the_skin before complete maturity, which would suggest that the 
larva does not find the conditions exactly normal. The following 
instance observed by a physician who is also a trained entomologist is 
of special value as showing the conditions of such an occurrence: 
Several years ago I saw, professionally, a boy 6 years of age who had been suffering 
for some months from the glands on one side of his neck being swollen and a fetid 
ulceration around the back teeth of the lower jaw of the same side. Three months 
treatment was of no avail, and the end seemed near; one day a white object, which 
was seen to move, was observed in the ulcer at the root of the tongue, which on 
being carefully extracted proved to be a large grub, which, from having frequently 
seen them, I recognized as a full-grown larva of Hypoderma. It was of the usual 
tawny color, about half an inch long when contracted, about one-third that thick- 
ness, and quite lively. The case ended fatally. This boy had been on a farm in 
Illinois the previous fall, where probably the egg was in some way taken into his 
mouth, and the larva found between the base of the tongue and the jaw suitable 
tissue in which to develop, coming to maturity at the same time with those bred in 
cattle. (Dr. John Hamilton, in Entomological News, Vol. LV, p. 219.) 
LIFE HISTORY AND HABITS. 
In certain points of life history and habit the two species agree. The 
adult flies are about half an inch in length and bee-like in appearance, 
the two species separated easily by characters to be detailed later. 
They appear during the summer months and deposit their eggs upon 
cattle, the act of oviposition being frequently accompanied by a great 
amount of annoyance to the animals, in some cases inspiring them with 
