19 
In that year, consequently on official enquiries being sent to 
myself as to the effects of the infestation on horses unused to 
the attack, and methods of prevention, I endeavoured to obtain 
serviceable practical information from local residents accustomed 
to deal with the matter, and in the following pages give an 
abstract of the information placed in my hands, of which I gave 
a full account, collated with previously published observations, in 
my Annual Report for 1895. 
The especially noticeable point in the life-liistory of this fly is 
that, like others of the genus Hippobosca, and also like the Sheep’s 
Spider Fly previously mentioned, it only lives actively in fly state. 
The flies do not lay egys, but the lame or maggots hatch, and are 
nourished up to their full growth separately within the abdomen 
of the females; at full growth they change to the pupal state, 
and are deposited in this condition (or ready quite immediately 
to turn to it) in the shape of white roundish bodies often mistaken 
for eggs, and very like them, excepting that they are notched at 
one end. These rapidly change from white to a dark brown colour, 
somewhat resembling a laburnum-seed, and within this pupanurn 
the fly forms, and in due time escapes by cracking off the notched 
end of its hard covering. (Figure at heading shows a puparium, 
nat. size and magnified, but as yet only partly coloured.) 
The Forest Fly, when at rest with the wings laid flat on the 
back (as figured, life-size and magnified, at heading), is three-eighths 
of an inch in length from head to the extremity of the wings; 
about a quarter of an inch in length from head to tip of tail. The 
shape is flattish, and the skin so hard and leathery that it is 
difficult to crush. 
The head is tawny yellow, with a dark stripe down the middle 
of the face ; the compound eyes dark and very large, occupying the 
whole sides of the head; ocelli, or simple eyes, wanting. The 
thorax , or body between the wings, has on each shoulder a large 
patch or irregular ring of tawny yellow, with more or less of the 
brown ground colour in the centre, some small pale markings 
along the middle of the hinder part of the thorax, and a pale spot 
in the centre of the scutellum (that is, of the small portion of the 
upper part of the thorax just preceding the abdomen). The 
abdomen is brown, grey below, and, like most of the fly, more or 
less beset with bristly hairs. 
Wings two, strong and membranous, slightly opaque and 
brownish in colour, and furnished with several strong dark veins 
placed along the front portion, as exactly figured from life at p. 18. 
c 2 
