ENTOMOLOGY. 
842 
them from their nefi: to the furface of the earth, whenever 
the weather is fine, that they may receive the benignant 
influence of the fun, carrying them back again as foon as 
the air begins to grow cold. If any accident difturb their 
nefi, and difperfe the pupae, they manifeft the greateft figns 
of diftrefs, feeking thofe which are loft and fcattered, 
placing them in fome fheltered place while they repair 
the neft, when they again tranfport them to it. 
The fecundity of infedts exceeds in an aftonilhing degree 
that of all the productions of nature. Reaumur calcu¬ 
lated the fecundity of the queen bee as,follows : he found 
that Hie laid in the two months of March and April 
12,000eggs, fo that the fwarm which left the hive,in May, 
confided of near 12,000 bees, all produced from one mo¬ 
ther : but this calculation falls ftiort of that which was 
made by Leeuwenhoek on a fly, whofe larva feeds on 
flefli, putrid carcafes, See. which multiply prodigioufly, 
and in a fliort fpace of time. One of thefe laid 144 eggs, 
from which he got as many flies in the firft month ; fo 
that, fuppofing one-half of thefe to be females, in the third 
month we (hall find 746,496, all produced in three months 
from one fly. M. Lyonet, in order to inveftigate the ge¬ 
neration of a moth, out of 350 eggs produced by a Angle 
female, took only Bo, from which he obtained, when ar¬ 
rived at their perfedt (late, 15 females; from whence he 
deduces the following computation : if 80 eggs give 13 
females, the whole brood of 350 would have produced 
63 ; thefe 65, fuppofing them as fertile as their mother, 
would have produced 22,750 caterpillars, among which 
there would have been at lead 4265 females, who would 
have produced for the third generation 1,492,750 ca¬ 
terpillars. This number would have been much larger, 
if the number of females among thofe which were feledted 
by M» Lyonet had chanced to have been greater. M. de 
Geer counted in the belly of a moth 480 eggs ; reduc¬ 
ing thefe to 400, if fuppofing one-fourth only of thefe to 
be females and as fruitful as their mother, they will give 
birth to 40,000 caterpillars for the fecond generation; 
and forthe third, fuppofing all things equal, fourmillions 
of caterpillars. It is not furprifing, therefore, that they 
are found fo numerous in years that are favourable to their 
propagation. But the Author of Nature has for our 
fakes limited this abundant multiplication, and wifely or¬ 
dained, that thofe fpecies which are the mod numerous 
lhall afford food to the greateft number of birds, fifties, 
&c. who, though conftantly employed on the deftrudtion 
of individuals, are unable to effedt that of any of the fpe¬ 
cies ; by which means an equilibrium is preferved, and 
no one fpecies preponderates. Few infects live long after 
their laft transformation, but their-fpecies are continued 
by their amazing fecundity ; their growth is completed, 
and their parts hardened fooner than thofe of larger ani¬ 
mals, and the duration of their exiftence is proportiona- 
bly limited. 
In the amours of the in fedt tribes, it is extremely curious 
to obferve the avidity with which the male and female 
approach each other. The facility with which the males 
fieek out the females, is hardly credible. If a female 
butterfly be concealed in a box, and there be any males 
within half a mile of the place, they will directly fly to 
the fpot, and hover over it. In fome genera the males 
are not fo adtive, but are eagerly (ought and caretled by 
the females : the incitements of the queen bee to ftimu- 
late the paflions of the male, are truly wonderful : fee 
A?is, vol. i. p. 793. The:- mode of contadt is by intro- 
million ; an operation which with them requires much 
time elfedtually to accompli fh ; after which the congrefs 
continues for many hours. The butterfly and moth are 
often feen in coitu for a whole day; and the common 
chafer beetle for upwards of twenty-four hours. But 
this furprifing duration of tire fexual embrace appears to 
be given them, becaufe it is perhaps the only one of their 
lives, and ferves to fecundate the whole mafs of eggs in 
the ovarium of the female. The male is afterwards (een 
retiring in a very languid Hate, to fome obfeure hiding- 
place, where it foon falls 3 prey to birds or reptiles;, the 
female feeks a nidus wherein to depofit her impregnated 
(lore, after which (he difappears, and in like manner falls a 
vidtim to death; the ends of her exiftence having been 
thus fulfilled. Were not this the cafe, infedts would 
multiply in fuch countlefs myriads, that the whole ex- 
panfe of our globe, and its furrounding atmofphere, would 
be found too limited to afford them fufficient room. The 
female, by a very furprifing. inftindt, almoft unerringly 
depofits her eggs where (he is certain her progeny will be 
fafely hatched, and fupplied with fuch food, and fuch 
means of pafling through their transformations, as nature 
has ordained for them. There are a great number of in¬ 
fedts which rejedt vegetable matter, and feek a nidus for 
their eggs in putrid flefh, or in living animals. But Reau¬ 
mur informs us, that thofe infedts which prefer dead flelh 
never attack living animals ; the fiefli-fly depofits her eggs 
in the bodies of dead carcafes, where her progeny receive 
the nourilhinent bed adapted for them ; but this fly never 
attempts to lay her eggs in the flefli of found and living 
animals. 
The infedts which principally depofit their impregnated 
eggs in the flefli of living animals, and which have not a 
little perplexed and embarralfed the refearches of both 
ancient and modern naturalifts, before they could difeover 
and afeertain their real habitudes, are the oeftri fpecies, 
commonly called gad-fly. The oeftrus bovis depofits its 
eggs in the back of cattle, under the (kin; which as they 
are hatched into larvae, produce a purulent tumour. By 
the pain it inflidfs, by making a nidus for its eggs, an ex¬ 
treme terror and agitation is occafioned, and the objedt 
of the attack runs bellowing wildly about, with its tail 
erect, and in a tremulous motion, and communicates the 
agitation to the whole affrighted herd. The larva is 
brown, having eleven fegments, with tranfverfe lines. 
When fufficiently matured, they drop from the nidus, to 
prepare for their winged (late. The oeftrus equi depofits 
its eggs on the hairs or cuticle of horfes, and always on 
thofe parts which can be licked with the tongue ; thefe, 
in the egg or larva (late, are conveyed with the tongue of 
the horfe, by licking the irritated part, into the ftomachj 
and pafling through the inteftines with the food, when 
fufficiently matured, are difeharged with the dung. Thefe 
larvae are commonly known by the name of bots. See 
-the engraving, fig. 19. The haemorrboidalis is another 
kind of equi: it depofits its eggs on the lips of horfes, 
occafioning a titillation, which caufes the animal, when 
attacked by it, to move its head violently up and down, 
and gallop,about with every appearance of diftrefs. The 
larvae are conveyed through the inteftines like thofe of 
the other fpecies.—The oeftrus ovis depofits its eggs on 
the inner margin of the noftrils of flieep, occafioning them 
to (hake their heads violently, and hide their nofes in 
duft or gravel. The larvae crawl up into tire frontal' 
finufes or horns, and when full fed, are again difeharged 
through the noftrils, to prepare for the fly (fate.—The 
oeftrus cuniculi, in like manner depofits its .eggs in the 
(kins of hares and rabbits. But the mod Angular of all, 
is the oeftrus hominis; which depofits its eggs under the 
(kin on the bellies of the Indians in South America, who 
go nearly naked. The larva, if difturbed, penetrates 
deeper, and produces an ulcer, which not unfrequently 
becomes fatal.—See the natural hiftory of thefe infects, 
under the article Oestrus, with corredt engravings of 
the different fpecies. 
Neither the larva, pupa, or eVen the egg-ftate of fome 
infedts are exempt from the attacks of others, who depofit 
their eggs in like manner upon them ; thefe, after having 
pa fled through the ufual transformation, become what is 
termed the ichneumon fly. An ingenious entomologift de- 
feribes the operation as follows : “ Oblerving fome cater¬ 
pillars feeding on a leaf, my attention was attracted by a 
little ichneumon fly, which appeared as if deliberating 
where to fettle. I was furprized to fee the caterpillars 
endeavouring by various contortions to get out of its way, 
and more fo whenever the fly poifed on the wing, as if 
going to drop. At length the parafite made its choice^ 
