(Estrid^. INSECTS. Glossina. 
tliey more particularly affect damp meadows, and appear 
in the perfect state in the autumn. This is the fly 
whose larva is commonl}’’ called the grub by farmers. 
Species belonging to the family Bornbylidae are amongst 
the most interesting of this tribe of insects. Their 
appearance is somewhat that of a small Humble-bee ; 
they fly with great velocity, and, like hawk-moths or 
humming-birds, suspend themselves by a rapid vibra- 
tion of their wings, hovering over flowers, and by means 
of their long proboscis extracting the nectar upon whicli 
they subsist in their perfect condition. The loud hum 
which they make whilst thus feeding, gives them a closer 
apparent resemblance to the Bombi. The family is for 
the most part exotic, some species being extremely 
beautiful. 
We must briefly refer to these insects in their 
annoying or destructive connection with quadrupeds. 
Those belonging to the genus Tabanus (see Plate 11, 
fig. 9, T, niger), are well known in this country under' 
the name of Breeze-flies from the loud buzzing noise 
which they make when on the wing; their approach 
strikes with terror whole herds of cattle, which instantly 
rush off with headlong speed on hearing the hum of 
these relentless tormentors. Different animals are 
attacked by different species of flies ; a few may be 
briefly enumerated. Fig. 172 gives a representation 
of Tabanus bovinus, and also a front and lateral view 
of the parts of the mouth. 
Fig. 172. 
Tabanus bovinus. 
The Tabanus bovinus attacks cattle, piercing their 
skins and sucking their blood in such a manner as to 
cause great pain ; the larva of this insect lives in the 
ground. 
THE (ESTRIDai, commonly called Bot-flies, attack 
various quadrupeds, each species of fly being parasitic 
upon a particular animal. Thus the Gad-fly {(Estrus 
bovis) attacks oxen ; this fly is about the size of a drone- 
bee, and not unlike it in colour; the female fastens 
herself on the back of the animal, piercing the skin, 
and then depositing an egg in the puncture. The 
larvae by their suction cause small abscesses, which 
increase in size as larvae grow, and may be frequently 
obsei'ved in great numbers on the backs of oxen and 
cows. AVhen the larvae are full grown, they emerge 
from these swellings and fall to the ground, creeping 
into any suitable hole for shelter, when they shortly 
undergo their change to their perfect condition. 
It would appear that some members of this family 
have been known even to attack man. Humboldt 
observed this in South America, the Indians being 
covered with small tumours caused by the (Estrus 
Von. 11. 91 
273 
Hominis. The (Estrus Equi deposits its eggs on the 
hairs of the horse, in such parts of the body that the 
horse, by licking, wdll be sure to convey them into its 
stomach; the larva is the cause of the disease known 
as the bots. (Estrus Ovis attacks sheep, the larva 
living in the frontal sinus of the head. The reindeer 
is attacked by the Estrus tarandi; the appearance of 
two or three of these flies is said to alai-m a whole herd 
of deer, so dreadfully are they tormented by them. 
The (Estrus follows the herd wheresoever it may retreat, 
and however rapid its flight ; it is not deterred, even 
should the deer flee to the snow-covered mountains. 
There is no escaping from these fearful tormentors ; 
the fly bores a hole in the skin of the deer, in which it 
deposits an egg. The larvae continue to feed until full 
grown, when their presence is known by a swelling 
observable on the hide of tlie animal as large as the 
egg of a pigeon. The attack of six or eight of these 
flies is sufficient so to emaciate the deer that great 
numbers perish. The Estrus Cervi attacks the fallow 
deer. Fig. 173 is that of Estrus trompe, with its 
larva and pupa. This species attacks the deer, depo- 
siting its egg in the nostrils of the animal; the larva 
feeds in the frontal sinus of the head. 
Fig. 173 
1, oestrus trompe ; 2, the larva ; 3, the pupa. 
The Zimb, described by Bruce the African traveller, 
is one of the most formidable and destructive species 
known ; this fly attacks its victim on all parts of the 
body, producing large bosses and ulcers, which in the 
end putrefy, and thereby inevitably cause the death 
of all animals which it attacks. 
Another equally destructive species of fly was dis- 
Fig. 174. 
covered by the celebrated African explorer. Dr. Living- 
ston; this is the Tse-tse described scientifically by Mr. 
Westwood ns Glossina morsitans. (Fig. 174.) This pest 
