THE BISCUIT-‘WEEVIL’[12] (_Anobium paniceum_)
‘Let us be merry,’ said Mr. Pecksniff. Here he took a captain’s
biscuit. ‘It is a poor heart that never rejoices; your hearts are not
poor. No!’—(DICKENS, _Martin Chuzzlewit_.)
The first things to notice about the biscuit-‘weevil,’ so familiar
to readers of Marryat’s novels, is that it is not a weevil at all,
and that it attacks a great many other comestibles besides biscuits.
The so-called biscuit-‘weevil’ is in truth an _Anobium_—_Anobium
paniceum_—a member of the family _PTINIDAE_ and is closely allied
to _A. striatum_, which makes the little round holes in worm-eaten
furniture, so cleverly imitated by the second-hand furniture-dealers.
Another species of _Anobium_ (recently re-christened _Xestobium
tessellatum_), a somewhat larger insect, is destructive in churches,
libraries, and old houses. Their mysterious tappings (which are really
efforts to attract the other sex—mere flirtations) are the cause of
much superstitious dread in the nervous, and this species is known as
the ‘greater death-watch.’
[12] Modern systematists now call the biscuit-‘weevil’ _Sitodrepa
panicea_.
[Illustration: FIG. 30.—Biscuit-‘weevil,’ _Anobium paniceum_. (From
David Sharp, _The Cambridge Natural History_, vol. vi.)]
But to return to the biscuit-‘weevil.’ The mature insect is about a
quarter of an inch long, and lives at large; it is the larva which
burrows into and attacks the dried biscuit—the ‘hard-tack’ of the
Navy. Less of a woodborer than its allies, it nevertheless attacks
almost any vegetable substance; and Butler tells us that ‘rhubarb-root,
ginger, wafers, and even so unlikely a substance as Cayenne pepper
have been greedily devoured by it.’ Several generations have been
known to flourish on a diet of opium, and it has been found in tablets
of compressed meat. Vegetable matter, even in an altered state—such
as paper—affords it an ample meal; and in one case the larva of
an _Anobium paniceum_ bored steadily in a straight line through
twenty-seven folio volumes in a public library, and so straight was the
tunnel that a string could be passed through it from end to end. In
one of our libraries at Cambridge some Arabic manuscripts were almost
entirely destroyed by the larvae, which do not hesitate to browse on
drawings and paintings and the dried paper of herbaria.
[Illustration: FIG. 31.—Early stages of _Anobium paniceum_. A, Eggs,
variable in form; B, larva; C, pupa; D, asymmetrical processes
terminating body of pupa. This larva is probably the ‘book-worm’ of
librarians. (From David Sharp, _The Cambridge Natural History_, vol.
vi.)]
The larva of this beetle is in truth a book-worm. Its interest for us
in the present series is, however, the disastrous infestation of ships’
biscuits, which frequently is so severe that the sailors ‘hard-tack’
is rendered uneatable. Heating, of course, kills it; but the biscuits
are still uneatable. The dead larvae are as unpalatable as the living.
The contrivance of biscuit-tins since Marryat’s time has done much
to lessen the evils. Tradition has it that a great firm and a great
fortune had their foundations laid, during the first half of the last
century, by the accidental contiguity of a baker’s shop and that of a
tinsmith.