74 
INSECTS. 
host, and reaching the ground bury themselves, and remain concealed until 
they emerge as perfect insects from the pupal stage. The three species above 
mentioned serve as types of the life-histories of the entire family, which contains 
in addition a large number of genera and species infesting various kinds of 
animals. Even man himself is not exempt from their attacks, and all kinds of 
domestic cattle and beasts of burden, such as reindeer, camels, and elephants, are 
liable to be infested with them. 
Two notices of the occurrence of 
larvae in human beings were pub¬ 
lished by John Howship in 1833. 
In both cases the larvae, named 
(Estnis humanus, were extracted 
from tumours, the sufferer in 
one case being a soldier in 
Surinam, and in the other a 
carpenter in Columbia. In 
addition to the mammals men¬ 
tioned, others, such as hares, 
rabbits, mice, and voles, often 
suffer from these parasites. Their 
larvae have also been met with 
in birds and frogs. Schneider, 
for instance, states that two larvae much resembling those of Hypoderma were 
obtained from under the skin of the head of a young sparrow, where they had 
produced two large hard tumours, and Krefft has given descriptions of specimens 
belonging to the genus Batrachomyia that were found living parasitically upon 
Australian froo-s. The larvae were situated between the skin and the flesh behind 
o 
the drum of the ear, and could be squeezed out through apertures in the skin. 
Forest-Flies,— Family Hippoboscidie. 
This family brings us to the second section (Pupipara) of the Cyclorrohapha, 
all the members of which are no less remarkable amongst flies for the strangeness 
of their appearance than for their method of development. They are all short and 
flat, with longish and powerful legs which enable them to run with great speed; 
some of them being entirely wingless, with the mouth-parts much reduced; but in 
the mode of their development they are absolutely unique in the entire order. In 
the first place only a single young one at a time is produced, and this, instead of 
being laid in the egg-stage, remains within the mother, nourished at her 
expense by means analogous to those which obtain in the higher mammals. When 
born, the young is either actually a pupa, or immediately assumes the pupa-state, 
being motionless, without segmentation, and entirely protected by a horny shell, 
which imparts to it the appearance of the seed of a vetch. The members of this 
section, which are mostly parasitic on birds or mammals, are referable to three 
families. Of these, the forest-flies are represented by several genera, all the members 
of which are parasitic upon mammals or birds, and are frequently spoken of as 
a, Adult fly ; 6, Larva from upper side ; c, Pupa from under 
side (all enlarged). 
