142 ZOOLOGY. 
of flies which destroy vegetables, and their size is so graduated that they 
are capable of destroying larve of all sizes, from those several inches in 
length, to such as do not exceed one twenty-fifth of an inch. ‘y 
Insects in their various states constitute the food of many beasts, birds, - 
reptiles, and fishes. Some, as the large grasshoppers, are sometimes dried 
and eaten in the Levant; some savage nations eat the large grubs found in 
rotten wood; and the cossus, which the ancients esteemed as a great deli- 
cacy, was a larva of some kind, and an allied one is now eaten in Brazil. 
Ants are eaten by the savages of Brazil, the formic acid probably replacing 
the vinegar used in civilized gastronomy ; whilst some of the lowest savage 
tribes devour their own vermin. 
The various species of blistering flies are employed under the name of | 
camtharides ; the genus Coccus furnishes the beautiful dyeing material 
eochineal; the galls formed on oak trees by insects of the genus Cynips, 
are used in the arts; and insects furnish honey, silk, and manna. 
Caprification is an art which has been practised trom a remote period. 
It consists in causing figs to ripen by suspending upon the trees branches 
of the wild fig tree Mamed caprificus by the Romans), which is infested by 
an insect which pierces the fruit and causes it to ripen. 
The indigenes of Brazil have made a curious surgical application of ants, 
many of which, when they attack with their mandibles, will allow them- 
selves to be pulled to pieces rather than let go. When one of these natives 
has received a cut, the sides of the wound are brought together carefully, 
and an ant adapted for the purpose is made to bite the conjoined edges, 
when the body is torn from the head, the process being repeated according 
to the length of the wound, so that the natives are often seen with rows of 
ant heads upon various parts of the body. 
Although insects are essentially terrestrial, there are families, the mem- 
bers of which swim upon the surface (as Gyrinus), or walk with the body 
raised above it (as Gerris, or Hydrometra), the tips of their feet touching 
the surface, and a few which walk upon the bottom (as Wepa). These are 
almost entirely confined to the fresh waters. Westwood, however, describes 
a genus (Micralymma) which inhabits the coasts of the sea between high 
and low water mark, under such circumstances that it must remain four hours 
under water at each tide, and he mentions other instances of Coleoptera 
remaining beneath salt water for shorter periods. (Mag. Zool. and Bot. ii. 
124.) According to Audouin, a small carabideous insect, Aepus fulvescens, 
passes a great part of the time beneath the sea, holding a small quantity of 
air among the bristles with which it is in part clothed; but whether it can 
abstract oxygen from the water when this is exhausted, has not been deter- 
mined. It is probable, however, that this power exists in the coleopterous 
genus Hlmis, and some allied ones, the species of which are small, tardy in 
their movements, and unable to swim. They live affixed to stones at the 
bottom of fresh waters, which are sometimes so rapid that the insects could 
not reach the surface and return to the position in which they are found. 
Among the insects which walk upon the water, the most remarkable is 
the genus /Halobates (allied to Gerris), which is found far at sea in the 
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