The 
decreafed very much in bulk, becoming at the 
fame time clear and perfpicuous ; as is likewife 
the cafe in Silkworms. The little line on the 
back, produced by the contents of the fto- 
mach, became likewife obliterated by degrees ; 
fince the Worm had now cleared its inteftines 
of all their grofs contents, afterwards lying in 
its web without any remarkable motion. 
July 13, I found fome dead in their webs ; 
but others had by that time affumed the habit 
of real Nymphs. Therefore it is evident, that 
thefe infects ftri@tly belong to the firft mode of 
the third order of natural changes; though I 
fhall not here refer them to it, becaufe they 
weave their webs, and are changed in a very 
obfcure manner under the earth. 
Some days after, that is July 18, I obferved 
many little black Flies iffuing, Tab. XLIV. 
Fig. rv. 4, out of thofe webs which I had taken 
out of the fand, and put into a dry box. This 
little Fly, being viewed with a microfcope,. 
thews itfelf divided as ufual into a head, thorax, 
and belly. Out of the fore part of the head 
arife two black horns, Fig. v. c. Thefe are 
placed before the eyes. ‘The thorax is ele- 
gantly divided, and fhews four membranaceous 
wings fixed to its fcapule, whereof the lower 
pair are covered by the upper, and all together 
cover the body. The upper wings are pro- 
vided with many pulmonary tubes, paffing 
through them, and near their extremities are 
marked dd with two blackith {pots. Six legs 
adhere to the loweft region of the thorax, ¢ e, 
that are divided by joints and two claws: they 
are of a colour approaching to black. ‘The 
abdomen alfo is black, and is divided into 
rings. Some of thefe Flies alfo had a tail, 
others not. 
The males I found had tails, but the fe- 
males none. If the laft rings of the females 
~ abdomens were prefled out, Fig. vi. ff, towards 
the hinder extremity, a fharp-pointed part was 
forced from thence; which being carefully 
examined with a microfcope, exhibited an in- 
ftrument like a faw, g fituated 4 between two 
pointed horny or bony little parts, and confe- 
quently fit for piercing the coats of leaves ; as 
J thall relate hereafter. On viewing the under 
part of the female’s body, I obferved that it 
grew white about the breaft, but that the legs 
were ruddy there. 
In what manner the eggs of thefe little creatures come into the 
W illow-tree. 
Mie e who call themfelves fearchers into 
nature’s fecrets, agree, that all ob{curer 
modes of generation muft be attributed to pu- 
trefaction as their caufe, which is the effect of 
moifture joined with heat. And this Opinion 
extends even to ftones ; for they obferve, that 
fome infects iffue from them. It is however 
very remarkable, that they cannot prove or il- 
luftrate that affertion by any one folid argu- 
ment, or fair experiment. They rely only on 
their own erroneous opinion, occafioned by an 
HIS TORY of I-N’SYHE-CTS. 
79 
But when I afterwards opened the female’s 
abdomen, I found perfect eggs there, exactly 
like thofe, which I before defcribed to be found 
in the tubercles of the leaves: fo that doubt- 
lefs, they are eggs of this Fly, which are found 
in the tubercles. This Fly is of the fame dif- 
pofition with thofe which proceed from con- 
fumed Chryfallides. Nor did Flies break out 
of thofe webs only, which I had put into the 
box: they likewife iffued out of the webs, 
which were yet buried in the moift fand. 
Hence I faw fome fuch little Flies lying dead 
in the fand, and others that had grown: faint 
and weak with the moifture. 
In fome other webs I found living Flies 
which iffued from thence fo quickly, tha: I 
could not catch them. I likewife opened fome 
males of this kind, and therein found the male 
organs of generation : however, I cannot now 
fay much of them ; becaufe I did not commit 
my obfervations thereon to writing. Thefe 
little infects are changed in a double manner: 
for when it happens, that their Worms, at the 
end of the year, creep into the ground, and 
there form webs; Flies do not proceed from 
them before the fpring of the following year. 
I cut open alfo the webs that were forfaken 
by thefe Flies; which indeed, they break in a 
very fingular manner: they make a round 
hole 7, Tab. XLIV. Fig. rv. in each, like that 
in a barrel. In thofe webs I found a fkin, 
which. the little creature caft off, when it be- 
came a Nymph, and alfoa tender fkin, which 
the Nymph, on being changed into a Fly, had 
afterwards cait. — 
After the creatures forfake the tubercles ; 
thefe latter grow dry entirely, and in fome 
days become contracted together. But as my 
curiofity had proceeded fo far as to keep all 
thefe little infects, as they are circumftanced 
in all their changes; hence I learned, that thefe 
tubercles could not be otherwife kept in the 
Willow leaves, than by filling them with a 
fufficient quantity of dry fand, and then leav- 
ing them to themfelves, until they grow dry: 
after this, the fand may again be eafily taken 
out of their cavity. Let this fhort defcription 
of this great and unheard-of natural miracle 
fuffice ; in which the wifdom and providence 
of God are clearer than the meridian fun. 
leaves of the 
univerfally prevailing error. I except only 
Dr. Francis Redi, who has pointed out a very 
different and much better way: for he, having 
firft, by irrefragible arguments and reafonings, 
deftroyed the {yftem of generation by putre- 
faction; yet not improbably infers, that thefe 
little infects, which are found in leaves, fruits, 
and the like fubftances, are generated there 
from the very foul and natural vigour of the 
vegetable which produces the fruits and plants. 
I fay, the opinion of this gentleman is not al- 
together 
