156 
After this Nymph has lived fome days, 
moving itfelf backwards and forwards in the 
water, and its tender limbs are ftrengthened, 
it burfts and cafts its {kin in the middle between 
thofe two horns or tubes, by the help of which 
it was before fufpended on the furface of the 
water; and after this, on account of the light- 
nefs of its body only, it remains on the fur- 
face, until its wings are expanded and dried 
with air; then the Nymph having affumed the 
form of a Gnat flies away, leaving its caft 
fkin fwimming in the the water, where it in- 
fenfibly decays. 
The Gnats of this {pecies *, which are beft 
of all known in Holland on account of their 
milchievous trunk or fting, are eafily diftinguith- 
ed into males and females. I exhibit the male 
in Tab. XXXII. fig. 1. and alfo a microfcopic 
view of it in fig. 11. Between this Gnat and 
its Nymph there is no other difference, ex- 
cept that the limbs are difpofed and placed 
in a different manner in the Nymph from what 
they are in the perfect Gnat. Hence, as the head, 
breaft, belly, &c. may be feen and unfolded in 
the Nymph, we may diftinguith all thefe things 
in the Gnat itfelf, but much more accurately, 
for the external {kin of the Nymph, which 
prevented the more diftinét view of all thefe 
parts, has been now, upon the laft change, 
thrown off. 
In the head of the male Gnat, I particularly 
exhibit, in the enlarged figure, the eyes, horns, 
and trunk ; as alfo. two other parts placed near 
the trunk or fting, between or under which the 
latter is properly placed: the eyes ¢ @ conftitute 
the greateft part of the head, as is the cafe in 
many other fpecies of infects. They are of a 
greenith colour, and they form: as it were an 
hexagonal piece of network, the divifions where- 
of rife in a globular figure. Near the eyes I 
reprefent the horns 44, which arife as it were 
out of two yellowith flefh-coloured little globes, 
and are beautifully divided into twelve black 
knot-like jeints, which are furrounded with 
hairs like tender flaxen threads. Toward the 
extremity of each of thefe .antenne is feen a 
circle, confifting of fix hairs placed in a circle ; 
above which appear the extreme ends of the 
horns furrounded or covered with yet {maller 
hairs. As to the other two long and crooked 
parts, between which the trunk or aculeus is 
obferved tobe fituated cc, I find them divided 
into three joints, befet with hairs toward their 
extremities, and moreoyer covered every where 
with a kind of brownith feathers, which re- 
femble, as the feathers of Butterflies do, the 
little fcales of fifhes. 
The trunk is of the fame colour, and is 
adorned d with the like {caly little feathers, but 
it ig not divided into joints, being immoveable 
in the middle ; though there are plainly fome 
divifions toward the end of it; and it is there 
The BOOK of NATURES of, 
likewife near the end regularly furrounded by 
five hairs on each fide of it. On full confi- 
deration of the whole, the part before defcrib- 
ed, and which we ufually call the trunk ¢, the — 
aculeus or fting of the Gnat, is nothing more 
than a fheath or cafe of the real fting e, which 
is reprefented in this figure only projecting, or as 
if thruft, out ofit. This fting is provided with. 
fo fharp a point, that I could never obferve the 
leaft breadth therein, with the beft microfcopes 
that I ufed in the year 1688. If you put the 
edges of the fharpeft razors, or the points of 
the fineft needles and lancets before the mi- 
crofcope, you will eafily fee that they have vi- 
fible breadth, and appear blunt, ragged, and dull. 
I do not find this fheath in all Gnats; and this 
is the cafe in that {pecies defcribed by Goedaert, 
the fting of which I fhould incline to think 
is very fhort, and lies rather in the mouth than 
in any fheath or cafe; fo that the fame thing 
feems to obtain here as in the Loufe kind, the 
fheath and trunk of which are alfo difcovered 
with difficulty, though thefe little creatures 
prick or fting vehemently, and give us great 
trouble by fucking our blood. 
Thus I obferve, with refpect to other in- 
fects, that there is great difference as to their 
{tings and trunks; fome of them have their 
probofcides eight times longer than others, be- 
' fides that the conftruGtion differs greatly in 
both, But I have elfewhere faid enough on 
- this fubje&, when I treated of the {wift Butter- 
fly, which is reprefented in the hiftory of the 
Rhinoceros Beetle, Tab. XXIX. But when I 
come to the Gad Fly I hall, from the obferva- 
tions I have made on the fting and trunk, offer 
fome reafons why many infects that feed on 
blood, ftill preferve life, through deprived for 
a long time of the blood wherewith they na- 
turally nourith themfelves. This queftion may 
certainly arife with refpect to Bugs, Fleas, and 
feveral fuch infects, and alfo in regard to the 
Gnat kind. I now return to the fubject and 
fhall give a more full explanation of the trunk 
of the Gnat. - 
The cafe or fheath of the fting, as I have al- 
ready obferved, is immoveable in the middle, 
but where it is united to the head it appears to 
be jointed. If one diffeéts it under the mi- 
crofcope, and very quickly breaks it off at a 
little diftance from the head, or-cuts it, Tab. 
XXXII. fig. 111. @, in its circumference, but in 
fuch a manner, as at the fame time to draw 
this broken cafe of the fting from the fting it- 
felf, which is placed on the infide ; this way 
at length the aculeus is plainly feen naked and 
difengaged from all impediments, in which 
ftate it could not be viewed before. When I 
firft made this experiment, I thought I had 
difcovered the whole aculeus in this manner : 
for I obferved an acute pellucid little part of a 
bright red colour 4, which confifted of a horny 
fc 
* We have in England three very diftin& kinds of Gnats: the largeft of thefe has brown eyes, anda black and white body ; 
the middle kind is altogether brown: this has the moft mifchievous bite of any. The third or {maller kind has a red breaft; this 
alfo bites feverely. ‘The Worms of all thefe are alike in form, and, what is very remarkable, they differ little in fize. We have 
belie thefe a multitude. of diftinét {pecies very fmall, which are, in the fen countries, very troublefome. 
or 
