HABITATIONS OF INSECTS. * ~Q61 
merely a mechanician, but a profound natural philosopher, well acquainted 
with the properties of air, it has another resource when any extraordinary 
violence threatens to overturn its slender turret. It forms a vacuum in 
the protuberance at the base, and thus as effectually fastens it to the leaf 
as if an air-pump had been employed! This vacuum is caused by the 
insect’s retreating on the least alarm up its narrow case, which its body 
completely fills, and thus leaving the space below free of air. In detach- 
ing one of these cases you may easily convince yourself of the fact. If 
you seize it suddenly while the insect is at the bottom, you will find that 
it is readily pulled off, the silken cords giving way to a very slight force ; 
but if, proceeding gently, you give the insect time to retreat, the case will 
be held so closely to the leaf as to require a much stronger effort to loosen 
it. As if aware that, should the air get admission from below, and thus 
render a vacuum impracticable, the strongest bulwark of its fortress would 
be destroyed, our little philosopher carefully avoids gnawing a hole in the 
leaf, contenting itself with the pasturage afforded by the parenchyma above 
the lower epidermis; and when the produce of this area is consumed, it 
gnaws asunder the cords of its tent, and pitches it at a short distance as 
before. Having attained its full growth, it assumes the pupa state, and 
after a while issues out of its confinement a small brown moth, with long 
hind legs, the Phalena Tinea serratella of Linné.1 
Some larvee, which form their covering of pure silk, are not content 
with a single coating, but actually envelop themselves in another, open on 
one side, and very much resembling a cloak; whence Reaumur called them 
“ Teignes @ fourreau a manteau.” What is very striking in the construc: 
tion of this cloak is, that the silk, instead of being woven into one uniform 
close texture, is formed into numerous transparent scales overwrapping each 
other, and altogether very much resembling the scales of a fish.? These 
mantle-covered cases, one of which I once had the pleasure of discovering, 
are inhabited by the larva of a little moth apparently first described by Dr. 
Zincken genannt Sommer, who calls it Tinea pailliatellas ‘ 
Various substances besides silk are fabricated into habitations by other 
larve, though usually joined together either with silk or an analogous 
gummy material. Thus Diwnea? lichenum forms of pieces of lichen a 
dwelling resembling one of the turreted Helices, many of which I observed 
in June, 1812, on an oak in Barham, The larva of another moth, which 
also feeds upon lichens, instead of employing these vegetables in forming 
Its habitation, composes it of grains of stone eroded from the walls of 
buildings upon which its food is found, and connected by a silken cement. 
These insects were the subject of a paper in the Memoirs of the French 
Academy 4, by M. de la Voye, who, from the circumstance of their 
being found in great abundance on mouldering walls, attributed to them 
the power of eating stone, and regarded them as the authors of injuries 
proceeding solely from the hand of time ; for the insects themselves are 
So minute, and the coating of grains of stone composing their cases is so 
trifling, that Reaumur observes they could scarcely make any perceptible 
impression on a wall from which they had procured materials for ages.5 
1 Goeze, Natur. Menschenleben und Vorsehung. Anderson’s Recreations, ii. 409. 
See above, p. 8 
: Reaum. iii, 206, 5 Germar’s Mag. fiir Entomologie, i, 40, 
x. 458, 5 Reaum, iii, 183. 
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