798 [Assembly 
The lambs should nowbe got up, and be dipped in or washed with a decoc¬ 
tion of tobacco—acheaj), inferior kind of which is on sale inmost of our 
stores for this purpose. Some are in the habit of washing their entire 
flock in this decoction, on the days of shearing, and this is a more effectual, 
but also a more laborious practice. This narcotic at once destroys the ticks, 
and has never been observed to nauseate the sheep, in the least degree. 
160. Grub in the head .—This is an affection which is caused by the 
larva or maggot, of an insect belonging to the family of gad-flies (CEs- 
tridje) which is another group pertaining to the same order of two¬ 
winged flies (Diptera.) The OEstrides resemble bees more than flies, 
in some respects, being large insects covered with hairs which often 
form bright colored bands. They are among the most singular and 
anomalous insects that are known. All the other two-winged flies pos¬ 
sess a trunk or proboscis through which they imbibe their nourishment. 
But the (Estrides are not only destitute of this trunk, but several of 
them have not the slightest vestige of a mouth—no opening whatever in 
the face by which to take in sustenance. It is in their larva state only 
that they receive nutriment ; and in this state each species lives within 
and draws its nourishment from some particular quadruped of the her¬ 
bivorous kind, none of them occurring upon the carnivorous. These 
larvae have three kinds of domicils in the animals which they infest. 
Some are cutaneous, living in tumors in the skin of the ox, the deer, 
the rabbit, &c. Others are gastric, subsisting in the stomach of the 
horse. Others are cervical, living in the frontal sinuses of the sheep 
and the reindeer. No one can contemplate the habits of these insects 
without being overwhelmed with surprise, they are so truly wonderful. 
In each instance the parent fly selects for its eggs a nest appropriate for 
the wants of the young insects that are to hatch from them. And as is 
well observed by the celebrated French entomologist, Macquart, in this 
selection is shown a foresight and sometimes a chain of reasoning 
which excites our profound admiration, not for the insect, for to it it is im¬ 
possible to attribute such forethought, but for that Supreme Intelligence 
by which it is prompted in its proceedings. How, for instance, can it be 
admitted that the bot-fly of the horse, an hour or two after it is hatched 
from the earth, knows all that it is doing, when after hovering some 
time in the air by the side of its victim, it deposits an egg upon his 
shoulder or else upon the inner side of his legs. Surely its own intel¬ 
ligence cannot inform it that that egg ought to be placed there so that 
the tongue of the horse in licking that spot will take off the young 
larva and draw it into his mouth and swallow it thence into his stomach, 
where its life must be passed. 
