FOREST FLY. 97 
‘‘T have made further enquiries, and find that they are only 
seen in the district from the beginning of June to the middle of 
September. 
«The neighbourhood from which they come is a wide valley running 
from Portmadoe to Beddgelert at the foot of Snowdon. Ponies are 
kept on the mountains on both sides in the summer, as well as a herd 
of ponies that are on the lowland both summer and winter. The 
village of Beddgelert being eight miles (without railway) from Port- 
madoc, and also being the nearest ascent to Snowdon, the horse traffic 
is very great along the road which runs under the mountain, especially 
in the summer season. 
‘« These flies were captured on one of the coach-horses on the above 
route by Joseph Davies, coach-driver, Prince Llewelyn Hotel, Beddge- 
lert.”—W. Morris Williams, Pwlheli, June 26th, 1895. 
The presence of the Forest Fly at such a great distance from its 
special habitat appears to be of a good deal of practical interest, as its 
unsuspected infestation in other localities might prove to be the cause 
of sudden unaccountable unruliness, sometimes causing a deal of 
trouble. 
Description or THE Fry.—The Forest Fly (Hippobosca equina, 
Linn., scientifically) is known also as the ‘Spider Fly,” from its 
spider-like appearance when the abdomen is distended by the single 
embryo; also as the “Flat Fly,’ from its flattened appearance under 
other circumstances; and also sometimes as the Horse Louse; locally, 
in the New Forest, the flies are often known as ‘“ Foresters.”’ 
The length of the fly from head to tip of tail is about a quarter of 
an inch; total length, including wings when laid flat along the back, 
three-eighths of an inch; the shape flattish; and the skin in great 
part so hard and leathery as to be difficult to crush. The general 
colour above deep shining brown, somewhat mottled with tawny- 
yellow. 
Head shining, rounded, flattened before, tawny-yellow, with a dark 
stripe down the middle of the face. Compound eyes dark and very 
large, occupying the whole sides of the head; ocelli, or ‘‘simple 
eyes,” none; antenne very short and sunk in pits, the end joint 
round, and bearing a long terminal bristle, and a shorter and 
smaller one. 
The mouth parts consist externally of a narrow proboscis-like 
apparatus, pitchy or blackish ; this is composed of two pieces which 
have a power of separation, but when applied one against the other 
form, by their concave inner surfaces placed together, a sheath, or 
elongate case, for the true trunk, or sucking-tube, which the insect 
can lengthen or withdraw at pleasure, and which to moderately 
powerful microscopic observation looks like a long yellowish some- 
: H 
