NOTES ON INJURIOUS INSECTS. 
FOREST FLY, 
Hippobosca equina, Linn. 
♦ 
* 
* 
Forest Fly, magnified (after Prof. Westwood); also life-size ; egg-like pupa 
and toothed claw (magnified). 
The “Forest Fly,” or “New Forest” Fly, as it is sometimes 
called in this country, known also by the names of the Spider Fly, 
Flat Fly, and Horse Louse-fly (scientifically, the Hippobosca equina), 
is a well-known trouble in the New Forest of Hampshire and its 
neighbourhood. 
This fly is to be found on various kinds of animals, as horses, 
donkeys, cattle, dogs, and cats, to all of which its presence in the hair 
is a severe annoyance. Donkeys will sometimes roll and kick for an 
hour in their endeavours to get rid of the fly; cats roll and tumble 
about as if in great distress ; but horses are the animals most especi¬ 
ally infested by it, and the almost intolerable annoyance caused by the 
fly to horses unused to it is a very serious consideration with regard to 
animals recently brought to the Forest. 
With their strong curved claws, bearing a kind of thumb-like pro¬ 
cess on each (see figure), the flies have an extraordinary power of 
holding on to the hairs, and besides can run to and fro, backwards, 
forwards, or sideways with a kind of crab-like movement, amongst the 
hair, or on the tender parts of the skin which they most frequent, so 
as by pulling, scratching, and tickling to perfectly terrify animals un¬ 
acquainted with the infestation. 
Horses unused to it become restive, and frequently unmanageable, 
plunge and kick and strike with their feet, in their endeavours to rid 
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