= 
The 
HISTORY 
of INSECTS. 
oO 
(ab 
Of the Worms that are found i [ome downy exccrefcencies of Oak-trees. 
HE Oak-tree affords fhelter and nourith- 
ment to as great a variety of infects as the 
Willow ; of this, at prefent, I thall produce 
only two inftances. The firft I take from the 
infeéts which breed within a kind of downy 
or foft excrefcence at the extremities of the 
branches; the fecond from certain other kinds 
which we find enclofed in a moft remarkable 
and furprifing manner, within the tubercles 
arifing on the leaves. This woolly or downy 
excrefence, of which I now intend to fpeak, is 
found in the form of a ball, Tab. XLV. Fig. 
vi. aaa, and is made up of a foft thready mat- 
ter, like wool or cotton: it is compofed of very 
delicate hairs, running in every direction fo as 
to form a very firm and fubftantial web ; but 
the hairs are not very ftrong in themfelves, for 
they are hollow, and look as if they confifted 
of fmall globules. They arife from the foot- 
talk, or from tops of the Oak branches 4, and 
fometimes from the leaf, which in many in- 
{tances fhoots, as it were, from the central 
part of the excrefcence c¢, fo as to appear en- 
tirely furrounded with this down. But the 
principal foundation of thefe hairs is no other 
than fome little oblong hollow bags or tubes, 
Fig. vit. d, if I may give them that name, 
which are at firft foft and tender like purfes, 
but afterwards harden to the firmnefs, as it 
were, of wooden pipes. 
Each of thefe cavities is conftantly found to 
contain one Worm, which lies hid, and grows 
in them, till it changes in the Summer months 
to a Nymph, properly belonging to the firft 
mode of our third order. Neverthelefs, as I 
have already often hinted, I rank thefe infects 
in the fourth order, becaufe they perform their 
changes in a dark and myfterious manner, 
which nothing but the indefatigable diligence 
and attention of the curious can bring to light. 
It is owing to this that thefe infects have been 
hitherto treated, not according to the laws com- 
mon to other animals, in which the great 
Creator has been pleafed more openly to ma- 
nifeft his glory, but according to falfe notions, 
fuggefted by our human ignorance and preju- 
dice. Imuft here, however, do juftice to the 
illuftrious Redi, who has treated the works of 
nature in a very different manner, and thereby 
refcued the operations of that great but fubor- 
dinate agent, from thofe thick clouds of dark- 
nefs which human error and ignorance had 
raifed about them: by what other name can 
we call that abfurd opinion, which attributes 
every thing to chance and putrefation. Cer- 
tainly, whatever allowances we may make on 
this occafion, to the generality of mankind, 
thofe among them, who would be thought 
people of fenfe and learning, are altogether in= 
excufable in countenancing fuch a thought: 
This grofs error is the natural confequence of 
mens manner of proceeding, when contented | 
with fitting quietly in their ftudies; and look- 
ing over books, they neglect to trace the ways 
of God, the great Author of all things, in his 
works, which furround us on every fide, neg- 
lecting them, to follow the delufions of their 
own feeble imaginations. 
The cavities now mentioned, are fometimes 
found to the number of ninety, or even a hun- 
dred, or more, growing through one another; 
and wrapped about in the woolly down, or cot= 
tony matter that islodged in the fame place: 
When the Worms, enclofed in them, have 
changed to Nymphs, and afterwards acquired 
their proper degree of ftrength, they each throw 
off a delicate fkin, and are thus turned to very 
fmall Flies ; then they bore with their teeth 
through both the little tubes in which they 
hitherto have lain concealed, and the down that 
furrounds them, and then iffue forth at a great 
many openings, Tab. XLV. Fig. vi. ee, ina 
very entertaining manner. On this occafion, 
ignorant fpeCtators are Joft in wonder, and form 
to themfelves. variety of fyftems to explain fo 
unufual an appearance ; but when they come 
to relate their opinions, we generally find them 
void of reafon, and altogether ridiculous. 
The Fly produced from thefe Worms, is di= 
vided into a head, thorax, and body, Fig.viir. Ohi 
The head is furnifhed with eyes, and it has 
two long antenne. From the upper part of 
the thorax {pring four membranaceous wings; 
that fhine like mother of pearl, and the upper | 
pair are adorned alfo with two black fpots, and 
with feveral very pretty ramifications of the 
nerves. ‘To the under part of the thorax are 
fixed fix tranfparent legs of a delicate redifh 
brown colour. The body confifts of feveral 
rings, and is armed, at its extremity, with a 
weapon of an oblong form that is plainly dif 
cernible: no doubt, this is the inftrument with 
which the infect pierces the Oak branches, in 
order to depofit its eggs within their fubftance. 
This Fly is altogether black in the body. f 
have not yet had the: good fortune of difco- 
vering its eggs, either in the excrefcencies 
wherein they are hatched, nor in the body of 
the female, as I never have diffeted any of 
them. I made the foregoing obfervations on 
the 26th of June, when a great many of thefe 
furprifing Flies iffued from their nefts, which 
they likewife continued to do, till the 8th of 
July. The males were fmaller than the 
females. 
ft 
Of 
