Flies on Cattle. 
65 
In this article it is proposed to describe the more impor- 
tant facts concerning some of the parasites of cattle and 
sheep most commonly met with in Great Britain, dividing the 
subject into external and internal parasites of cattle and of 
sheep, and giving in each case the treatment recommended. 
External Parasites of Cattle. 
The external parasites usually produce their effects by local 
irritation, while the diseased condition of the skin is often 
mainly the result of self-inflicted injury, caused by the host in 
attempting to rid itself of the irritant. Parasites which pierce 
the skin may, however, produce sores, or be the carriers of 
disease germs and the means of propagating serious systemic 
or local conditions, in addition to the irritation associated with 
their puncture. 
Flies. — All insects have six legs and jointed bodies ; the 
class includes the Diptera or two-winged insects, commonly, 
though not always correctly, called “ flies.” In the perfect 
state, flies are temporary parasites ; some only bite the skin, 
and give rise to sores, which are aggravated by the attempts 
of the animal to dislodge its unwelcome guests ; others, 
not truly parasitic, may merely convey infective matter, 
with which they have become soiled from contact with 
diseased parts, but may thus be important factors in spreading 
contagious disease. 
Of the biting “ flies,” cattle are sometimes attacked by the 
breeze or gad fly ( Tabanus ), — resident in woods and pastures, 
and which in its flight makes a buzzing noise — the forest fly 
( Hippobosca ), the cleg or grey fly ( Stomoxys ), and the gnat 
( Culex ). These, and probably flies of other species, when, as 
during the past summer, circumstances favour their existence, 
may annoy, cause unrest, and occasion loss of flesh and milk, 
to which self-inflicted injury is often added. The legs of 
cattle appear to be more generally affected by flies of this 
class, which are found more commonly in certain districts 
than others. On rare occasions, the small blinding breeze fly 
( Chrysops ), which specially attacks the eyelids, may induce 
extensive inflammation, leading to temporary blindness. 
The means at our disposal for preventing the attack of 
such flies are referred to under the next section (Ox Warble 
or Bot Fly). 
Ox Warble or Bot Fly. — Of all parasitic diseases of the skin, 
probably none is more familiar than that usually referred to as 
“Warbles.” It is well known that the lumps, which are 
perceived in the skins of cattle from January to May, contain 
the larvae or maggots developed from eggs deposited on the 
skin or hairs in summer by a fly. For many years, it has 
VOL. 67. F 
