• ••• '
ISO B R I T I S H BLOOD-SUCKING FLIES
arc attacked by this fly it is easily known by the extreme terror and agitation
of the whole herd ; the unfortunate object of the attack runs bellowing from
among them to some distant part of the heath or the nearest water ; the tail
from the severity of the pain is held with a tremulous motion straight from the
body, and the head and neck stretched out to the utmost ; the rest from fear
usually follow to the water, or disperse to different parts of the field. And
such is the dread and apprehension in the cattle of this fly that I have seen one
of them meet the herd when almost driven home and turn them back, regardless
of the stones, sticks and noise of their drivers ; nor could they be stopped till
they reached their accustomed retreat in the water."
Metaxa (1816) writing of " Oestrus bovis L. : Asibis of the Romans : Asillo
makes the erroneous assertion that the females bore a hole with their ovipositor
into the skin of their victims. It is also stated that the flies "in
the warmest hours of the day dart upon the backs of the oxen, making a
whistling noise the while. . . . The puncture made by this Oestrus is most
painful, and the oxen on simply hearing it at a distance take to flight." For
a reference to, and translation from Metaxa's work, the present writer is
indebted to his friend, Mr. Wilham North, M.A., of Sidney Sussex College,
Cambridge.*
It is true that the warble-flies (the larvae of two species of which, Hypoderma
lineatum Vill. and H. bovis Degeer are found in " warbles " or sacs beneath
the skin of the backs of cattle, while those of a third British species, H. diana
Brau. similarly infest red deer) are incapable of biting, and that the ovipositor
is unable to pierce the skin, the eggs being merely attached to the skin of the
victims. Yet, although absolute proof is wanting, and must under the circumstances
of the case be extremely difiicult to obtain, it is thought that the approach
of a Hypoder^na is terrifying to cattle, while modern observation shows that
these animals, like horses, are indifferent to the attacks of Tabanidae. Thus
the author was informed by the late Lt.-Col. Yerbury that cart-bullocks in
Ceylon are in no way terrified by the attacks of horse-flies, and this statement
is corroborated by Lt.-Col. Bingham for cart-bullocks in Burma. In Germany
the author has seen horses in harness contentedly feeding from a nose-bag
though attacked by several large T. bovinus, the bites of which, when the flies
were disturbed, caused great drops of blood to roll down the horses' skins.
Beyond a kick wdth the hind foot or a swish with the tail the horses appeared
to take no notice of the flies, either when actually sucking blood or when flying
round preparatory to settling. According to Col. Bingham elephants in Burma,
though sorely pestered by horse-flies, which make them bleed in a moment,
are equally unconcerned. Only when a bite is inflicted on a particularly sensitive
spot will the elephant lift a hind foot, or give a swish with its tail.
* Compare also Moufet (1634, p. 62), referring to the Bot-fly under the name " Asilus " : " It does
not ding, nor suck blood, but merely pierces by means of the sting in its tail, and in order to attack
horses flies in pursuit of them for a very long distance. By instinct horses fear this fly and shudder at
its very touch, often striving with tail, feet and lips to drive away the bloodthirsty assailant. There are
those who hold that this fly does not pierce by means of a sting, but affixes dung to the hairs of the horse
by means of its tail, from which troublesome nits are generated," But he cautiously adds that it is better
to reserve judgement on a matter so improbable.—H.O.
• G A D - F L I E S ' 151
The following letter, received by the author many years ago from his
friend Mr. Albert Piffard of Felden, Boxmoor, an excellent entomologist and
an accurate observer, may appropriately be printed at this point.
" My reasons for supposing that Oestridae terrify cattle, and that Tabanidae
do not, are founded upon the following easily observed facts. Haematopota
quite commonly settles on horses in harness and sucks their blood, but even a
nervous horse seldom becomes at all restive unless the fly attacks the belly or
some very sensitive part, and even then I have never known of one becoming
panic struck. I have repeatedly noticed Tabanus bromius on cows and killed
It full of blood, but never saw a cow display alarm or irritation from its presence.
Now Tabanidae fly quite noiselessly * ; but Hypoderma bovis, as I was told by
Dr. Capron, and Gastrophilus equi, as I know from hearing it, make an alarming
sound a little like but much louder than that produced by Sirex gigas (The
Great Tailed Wasp) when on the wing. I have many times seen cattle maddened
by the gad-fly, and on one occasion I made a capture of an allied species under
somewhat similar circumstances. I had noticed an old screw in a pasture
plunging and capering like a colt, and on approaching perceived a fly circling
round him with a terrible buzzing : I took it and it proved to be Gastrophilus
equi.
" Many years ago a French peasant girl, then nursemaid to my children,
used to amuse them and mystify the cowman by standing at the gate of the
meadow and causing the cows to rush about with their tails cocked. On my
inquiring how the little miracle was worked, she showed me that by making a
hissing sound scarcely audible to me a few paces off, she alarmed the cattle at,
I think, quite one hundred yards distance. This, at least, shows that the
sound is sufficient to cause the panic, and I have never seen the effect produced
by the bite of a Tabamis.
" I should imagine that the trick of hissing for the fly must be a very
ancient one, and that the passage in Isaiah, Chapter VII, verses 18, 19—' And
it shall come to pass, in that day, that the Lord shall hiss for the fly that is in
the uttermost part of the rivers of Egypt, and for the bee that is in the land of
A s s y r i a - r e f e r s to this. Possibly the 'fly' and 'bee' alluded to may be
Hypoderma bovis and Gastrophilus equi respectively ; the latter, as you know,
is not very unlike a bee." j
Theobald (1904, pp. 127, 130), writing of H. lineatum Vill., and H. bovis
De G., says : " The flies, by frightenmg stock when on the wing, and on the
lookout for a host on which to deposit their eggs, frequently cause loss among
' in-calf ' cows by making them stampede about the fields. . . . They produce
a low audible hum, which causes the animals to stampede and seek shelter."
Colonel Yerbury, who devoted himself for many years to the collection and
* This is an error as regards the larger species such as Tabanus sudeticus and T. bovinus which
make a deep hum when on the wing.—E. E. A.
t Mr. Piffard's statements are confirmed by a Cheshire farmer, Mr. C. Alcock of Castle Hill
Rmgway Mr. Alcock stated in conversation (July 1939) that cattle are not affected by the presence
of horse-llies, but that the noise of the warble-fly causes them to " gad " ; he further stated that he
had sometimes amused himself by imitating the buzz of the warble-fly and thereby causino-
" g a d d m g " . — F . W . E d w a r d s . ^