90 The BOOK of 
NU ASTER ULR JH 3 Sor, 
Of WV orms Sound within the tubercles or fwellings of the flinging Nettle. 
qi. is very remarkable, that even in fome 
{tinging Nettles we meet with Worms, 
which are deftitute of feet, and derive their 
origin from a very fmall but yet difcernible 
egg. Thefe excrefcences are found on the 
Nettle, in a great variety of forms. Some are 
produced upon the ftalk, Tab. XLV. Fig. 11. 
a; others on the ribs of leaves, or the tender 
buds, 4: fome again lie confufedly, here and 
there, all over the furface of the leaves, c. 
The fubftance, of which thefe fwellings are 
formed, is very hard and compact, which 
makes it an eafy matter to crack them. In 
colour they are fomewhat of a yellowith green. 
On the 28th of June I found a great many, 
both eggs and worms, in thefe fwellings. The 
{malleft of them contained each one egg; 
thofe fomewhat larger, a worm; and the 
largeft of all, which were compofed of two 
or three of thefe fwellings growing together; 
afforded fhelter to two, three, or even four 
Worms of different fizes, and all this at one 
time. 
The largeft of the Worms I difcovered at this 
period, were exactly of the fame fize with that, 
whofe form, taken from the life, I exhibit in this 
figure, Fig. 11.d. This Worm, viewed with 
a microfcope, appeared fomewhat broad, and de- 
prefied in the middle, e, and armed on its fore- 
part with a delicate flender fnout,?/; its body 
was almoft white, but a yellow ftreak appeared 
within it, which the Worm’s tranfparency ren- 
dered very difcernible. I found afterwards that 
this was an inteftine, and that the colour of it 
was entirely owing to its contents. The {kin of 
thefe Worms had fome delicate hairs {cattered 
loofely here and there over its furface, g. 
On opening fome more of the fwellings on this 
plant on the third of July, I found fome of the 
enclofed infeéts were changed into Nymphs. Such 
of them as had lately caft their {kins were white, 
but the older Nymphs exhibited a variety of 
colours. ‘Thefe Nymphs belong to the firft mode 
of the third order; for it was eafy to difcover in 
their limbs the form of the future Fly. They 
very plainly appeared to confift of a head, thorax, 
and belly. In the head, I could difcern two re- 
markable eyes, Fig. ry. 6, of a reticular form, 
which were beginning to look red; and on the 
fides of the head the horns, legs, and wings, 
were curioufly folded up, and might be feen 
{pringing from the thorax. The rings of the 
body were very confpicuous, and it had a little 
tail bent back, fo as to lie over them in a very 
elegant manner, 7, All thefe parts, the legs and 
wings excepted, were changed by degrees from 
white to yellow, which they afterwards loft, to 
aflume a deep brown colour, and finally a perfect 
black. 
On the ninth of July, many of thefe tubercles 
were burft open; and they no lenger contained 
any infects, but only fome of the caft-off fins. 
This gave me room to judge, that the Nymphs I 
had obfervedon the third of thismonth, had pafled 
inthe interval from that time, into the Fly-ftate, 
and my conjecture was confirmed by what hap- 
pened in the tubercles I kept at home in boxes. 
To me it appears probable, that all thefe tu- 
bercles open of themfelves *, at the time when 
the enclofed infect has its wings, and is in rea- 
dinefs to launch out into the air; and this may 
ferve to account for my finding Nymphs at this 
very time, in fome other tubercles which re- 
mained unopened, which had not as yet acquired 
their proper colouring, nor ftrength enough to 
caft their fkins. 
The Fly thus produced 2, is furnithed on 
the forepart of its head, with two longith black 
horns. The head is of a dutky brown, with 
a fine tinge of blueifh green: and the eyes are 
red: from the upper part of the thorax arife 
four membranaceous wings, and from the 
lower fix legs of a colour between red and 
white. In the males the body ends in a little 
tail, divided into two ftiff hairs, or in a forked 
manner; fo that this Fly is to be referred to 
‘the order that takes its name from this circum- 
ftance, Bifete; but in the females, this part 
terminatesin a pointed weapon. ‘The breaft 
and body of thefe Flies is of a very delicate and 
refplendent green, like that of Spanith Flies, 
or Cantharides, fo as to afford, when viewed 
with the microfcope, a moft entertaining and 
elegant fpectacle. unfortunately omitted dif- 
fecting thefe infeGts. To. preferve thefe Flies 
and their Nymphs, I extend their limbs on 
white paper, and there faften them down with 
a little moift ftarch, for they are too delicate 
to be fixed upon pins. 
* So far as I have obferved in thefe cafes, the Fly, when perfect, gets out of the tubercle two ways, but both are by violence, not 
by the natural opening of the tubercle. 
way out: in other initances, 
fucceffive fwellings of the Fly’s head, 
Y 
the covering is by this time become nothing more than a thin, ‘ ; 
which have been mentioned on a former occafion, burft the rind and let it out. 
Sometimes the fubftance is fo hard, that the Fly is forced with great labour, to gnaw its 
dry, and brittle membrane; and the 
Of 
