ICHN 
the fervices they perform, in deftroying caterpillars, plant- 
lice, and other infefts, that they have derived their name: 
thefe animals are devoured by them, as the genuine ich r 
jieumon deftroys the crocodiles. See the article Viverra. 
As the fpecies and varieties of the ichneumon? are pro- 
digioufly numerous, fo their manners are extremely diver- 
flfied. In the general outlines of their charafter, they all. 
agree, being remarkable for their depredations among the 
infeff tribes. In fome, the female is furniihed with a 
wimble, attached to her abdomen; and with this iriftru- 
ment, though delicate, (lie is capable of piercing-through 
lime and plafter. The larvae of wafps and rnafon-bees are 
the devoted prey of this fpecies, which no fooner efpies 
one of their nefis, than with its wimble it perforates the 
mortar of which it is conllrufted. This operation, which 
is performed with lingular dexterity, is no fooner finiflied, 
than it depofits its eggs.in the infide, to the number of 
one, two, and fometimes more. Some'are contented with 
gluing their ova to the {kin of a caterpillar, while others 
penetrate through it, and depofit the egg in its body. 
The ova hatched within the caterpillar, after being quick¬ 
ened into life, preys upon the inteftines of that animal, 
without,- however, deltroying its vitals. Upon the. Ijfe 
of the one animal that of the other feems to depend ; and 
the ichneumon fpares the caterpillar upon which it feeds, 
till it is about to enter into its chrylalis ftate. In the 
mean time, the caterpillar in which it is enclofed is ap¬ 
parently healthy, and prepares to undergo the fame tranf- 
fofmation ; a function which it'is feldom able to accom- 
plith, becaufe the interior parts eflential to the butterfly, 
though not to the^worm, are deftroyed. Often thefe ca¬ 
terpillars, which have been the cradle of thirty or forty 
ichneumons, are feen fixed to the bark of a tree, as if they 
were fitting upon their eggs; and it is difcovered that the 
larvae which were within their bodies have fpun their 
threads, with which, as with cords, the unhappy caterpil¬ 
lar has been fafler.ed down, and perilhed milerably. 
An ingenious entomologift defcribes the operation as 
follows: “Obferving fome caterpillars feeding on a leaf, 
my attention was attracted by a littlp ichneumon-fly, which 
appeared as if deliberating where to fettle. I was fur- 
* prifed to fee the caterpillars endeavouring by various con¬ 
tortions to get out of its way, and more fo whenever the 
fly poifed orr-the wing, as if going to drop. At length 
the parafite made its choice, and feated itleif on the back 
of one of the largeft of the clufter. It was in vain that 
the caterpillar endeavoured to diflodge the enemy ; and 
its anguifli at intervals appeared intolerable, in confe- 
quence of the wounds given by the fly. At every wound 
the poor caterpillar wreathed and twitted its whole frame, 
endeavouring to difengage the enemy, fometimes aiming 
its month towards the place; but it was all in vain; its 
little tormentor frill- kept its place. - When it had inflict¬ 
ed thirty or forty wounds, it took its - flight with a vifible 
- triumph ; in each of thefe wounds the ichneumon had 
depofited an egg. I took the caterpillar home to obferve 
the progrefs of -the eggs which were thus placed in its 
body, taking care to give it a frefh fupply of leaves from 
time to time ; it recovered to all appearance from the 
wounds, and from that time, for the (pace of four or five 
days, feemed to feed with its ufual avidity. • The eggs 
were all hatched into fmall oblong voracious worms, which 
fed from the moment of their appearance on the flefli of the 
caterpillar in whole body they were inclcfed, and feemingly 
without wounding the organs of relpiration f or digeftion ; 
and, when they had arrived at their full growth, they ate 
their way out of the fides of the animal. Thefe are what 
have vulgarly been called caterpillar-eaters. The caterpil¬ 
lar thus attacked by the larva of the ichneumon never ef- 
capes, its deftruftion is infallible ; but then its life is not 
■ taken away at once ; the larva, while it is feeding thereon, 
knows how to fpare the parts which are eflential to life, 
becaufq its own is at that time tied up in that of the ca¬ 
terpillar. . No butterfly is produced from the caterpillar ; 
EUMON, 73 1 
the worm6 that feed on it are no fooner out of its body, 
than every one fpins its own web, and under this they 
pafs the pupa ftate, in order to introduce them to their 
winged form.” 
One of the moft familiar examples of this procefs is af¬ 
forded by the well-known caterpillar of the common 
white butterfly, which, in the autumn may be frequently 
obferved to "creep up l'ome wall or other convenient fur- 
face, in order to undergo its own change into chrylalis ; 
but in the fpace of a day or two a numerous tribe of fmall 
maggots will be feen to emerge from it, and immediately 
proceed to envelope themfelves in diftinft yellow fllken 
cafes; the whole forming a groupe around the caterpillar. 
Other Irnall fpecies of ichneumon pierce the Ikins of newly- 
changed chryfaliies of butterflies and moths, in which 
their larvae remain during their own incomplete ftate. 
Others again are fo very fmall that the female pierces even 
the eggs of moths and butterflies, and depofits her own 
in each. Other ichneumons are of very confiderable fize, 
and the females of thefe feleff fome large caterpillar for 
their vidlim, as thofe of the larger Sphinges, fuch as the 
S. liguftri, convolvuli, See. or one of the large and mid- 
dle-fized moths, as the Phalaena vinula, q'uercus, &c. &c, 
Thefe large ichneumons are generally bred in fmall num¬ 
bers, and fometimes the female depofits but a fingle egg 
in the feledfed caterpillar. 
The feeming feverity of the procefs ordained by..nature 
for giving birth to the genus Ichneumon, may be much 
diminifhed by l’uppofing, (what all the enfuing pheno¬ 
mena leem to imply,) that, after the firlfc operation of 
piercing the (kin and depofiting the eggs is performed by 
the female ichneumon, the caterpillar feels no acute pain, 
the included enemies feeding only on its juices, and evi¬ 
dently fparing the more important organs; fo that it lofes 
its life by a very gradual decay. It was the want of an 
exaft knowledge of the genus Ichneumon that proved fo 
confiderable an embarraflinent to- the older entomologifts, 
who, having feen a brood of ichneumons proceed from the 
chryfalis of a butterfly, could not but conclude that the 
production of infefts was rather a variable and uncertain 
operation of nature than a regular continuation of the 
. fame fpecies. The obfervations however of Swammerdam, 
Malpighi, Roefel, and others, have long fince removed 
the dieffiulties which formerly obfcured the hiftory of the 
infe£t tribe. 
The numerous fpecies of Ichneumon are diftributed 
into fix divifions, or families, from the colour of their 
Icutellum and antennae, as follow : i. Thofe with a 
iwhitiih fcutcheon, and antennae annulated with a whi- 
ti(h band. 2. Thofe which have a white fcutcheon, and 
antennae entirely black. 3. With a fcutcheon of the 
fame colour as the thorax; the antennae encompafled with 
a fillet. 4. With a fcutcheon of the fame colour as the 
thorax ; and antennae black and Cetaceous. 5. With Ce¬ 
taceous clay-coloured antennae. 6. With fmall filifprm 
antennae, and the abdomen oval and (lender. 
From what lias been laid, it will be readily ■ inferred, 
that the whole of this genus are pa-rafitical, that is, derive 
their fupport and nourilhmenc from other inlects, fome de¬ 
pofiting their eggs in the larva, others again in the pupa, 
. and fome even in the ovum or egg itfelf, the contents of 
which, minute as they are, are Cufficient to fupport the 
young larvae until their change into the pupa ftate. Some 
depofit only one egg in a place, as the Ichneumon ovulo- 
rum, and others again a great number, as the Ichneumon 
puparum. See. but whether the egg is placed in the pupa, 
larva, or ovum, the deftrucSion of the fofter-parent is ine¬ 
vitable. To treat of each fpecies-would fill - a volume : 
we (hall therefore lelecl as, an example, the Ichneumon 
manifeftator, an infect truly wonderful in its formation, 
and which in a diitinguifhing manner unites the two pro¬ 
perties of a penetration and forefight-bordering on faga- 
city, in finding a fuitable fituation for depofiting its own 
eggs, and alfo rendering futile and abortive the labour 
and. . 
