are ufually feen placed near one another, and a vaft number o f
thefe clufters are found on the fame tree; the end of each o f thefe
filaments is terminated by a fort o f fwelling, or tubercle, o f the
fhape o f an egg. They have generally been fuppofed to be o f
vegetable origin, and that they were a fort o f parafitical plant,
growing out o f others. There is a time when thefe egg-like balls,
which terminate every one o f thefe filaments, are found open at
the ends; in this ftate they very much refemble flowers, and
have been figured as fuch by fome authors, though they are only
the eggs out o f which the young animals had been hatched and
made their efcape. I f thefe eggs are examined by a microfcope,
a worm may be difcovered in them ; or they may be put in a box,
in which, in a proper time, they will produce an infeft, which,
when, viewed with a microfcope, will be found to be the true lion
pucerorr.
Divine Providence mftrufts the infefts, by a lower fpecies o f
perception, to depofit their eggs in fituations- where their young
ones will find the nourifhment that is moll convenient for them.
Some depofit their eggs in the oak leaf, producing there the red
g a ll; others chule the leaf o f the poplar, which fwells into a red
node or bladder; to a fimilar caufe we are indebted for the red
knob which is often feen on the willow-leaf, and the three pointed
protuberances upon the termination of the juniper branches.
The leaves of the veronica and ceraftium are drawn into a globular
head by the eggs of an infeft lodged therein. The phalaena
neuftria glues it’s eggs with great fymmetry and propriety round
the fmaller branches o f trees. Fig. I , Plate X. reprefents a
magnified view o f the neft of the eggs taken off the tree after the
caterpillar had eat it’s way through them; the ftrong ground-work
o f
o f gum, by which they are connected and bound together, is very
vifible in many places; they llrengthen this connection further,
by filling up all the intervening fpace between the eggs with a
very tenacious fubftance. The eggs are cruft aceous, and fimilar
to thofe o f the hen. Fig. 3, Plate X. is a vertical feftion of
the eggs, fhewing their oval fhape. Fig. 5 is an horizontal
lection through the middle o f the egg. It is not eafy to defcribe
the beauty o f thefe objects, when viewed in the lucernal microfcope
; the regularity with which they are placed, the delicacy o f
their texture, the beautiful and ever-varying colours which they
prefent to the eye, give the fpcftator a high degree of rational
delight.
Some depofit their eggs in the back o f other infefts; thefe,
after having paffed through their various transformations, become
what is termed an ichneumon fly. In the Lapland Alps there is
a fly covered with a downy hair, called the rhen-dcer gad-fly,
oeftrus tarandi, Linn. It hovers all day over thefe animals,
whofe legs tremble under them; they prick up their ears, and
flee to the mountains covered with ice and fnow, to efcape from
a little hovering fly, but generally in vain, for the infeft but too
foon finds an opportunity to lodge it’s egg in the back o f the
deer; the worm hatched from this egg perforates the fkin, and
remains under it during the whole winter ; in the following year
it becomes a fly. The oeftrus bovis is an equal terror to oxen ;
the hippobofca equina to horfes ; oeftrus ovis * to the fheep, &c.
K k 2 The
* Oeftrus ovis in nafo five finu fronds animalium rumenantium. Linn.