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cycle from egg to beetle may be prolonged to two years or more, it usually lasts
only a year. These larvae infest both coniferous and hard-wood objects and may
invade heart-wood as well as sap-wood.
The common furniture beetle is the Anobium punctatum. It is small (i/io to
1/4 inch) and is reddish brown to dark brown in color. The insects usually emerge
in June or July, leaving their pupal beds or cells in the wood at that time. Fre-
quently they are found crawling on walls and ceilings. They pair then and the
females lay their eggs in cracks and crevices of wood. The young larvae bore in,
going first at right angles and then along the grain. As they grow, they work to-
wards the surface and gnaw out a small cell which serves as a pupal bed. From
this the beetle emerges. The largest of the furniture beetles is the Xestobium rufo-
mllosum or death watch beetle. It is one fourth to one third inch long and brown
in color. Its pupation occurs in the spring as does that of the Anobium but the
beetles do not emerge until autumn or even as late as the following spring. It is
comparatively rare and its traces distinguish it from the Anobium: the exit holes
are larger and the dust is in coarse pellets. Two other kinds of beetles that infest
furniture are so rare as not to have acquired popular names. They are the
Ernobius Mollis and the Ptllinus Pectinicronis.
It appears that the Anobiids prefer old wood, possibly because of chemical
changes that improve it as food, or because of the presence of micro-organisms, or
simply because it offers better places for egg-laying. In panel paintings the tunnels
made by larvae not only bring about a general weakening of the support, but
also establish areas of particular weakness where the paint is apt to collapse and
be entirely lost. The ground and paint film offer no food and it is often found that
the larvae run their tunnels directly beneath them. Pupal beds are made there
and beetles emerge through the paint, leaving behind them tubular openings next
the ground and completely hidden. These empty tunnels afford no resistance to
the general shrinkage of the panel and when that occurs, the paint above them
* buckles' or * tents' and frequently flakes off entirely. The presence of such
tunnels in a painted panel is indicated by buckled films, by marked or thread-like
cracks following, usually, the grain of the wood, by visible exit holes, or by a
lack of resonance if the tunnels are sufficiently numerous. In many instances
there are but slight indications on the painted surface; probing the panel from the
reverse will give some evidence about the general state of the wood. Where
ground and paint films are thin and uniform, a radiograph may show the location
of tunneled wood, but as a rule the density contrast of pigments is so great as to
conceal that In the support.
The activities of the termite (reticulitermes ftavipes) are similar to those of the
beetle. It appears, however, that prevention or elimination of them is less a
matter for individual objects than for structural changes in buildings. (This is
explained by Morgan Marshall in * The Termite Menace,' Technical Studies^ IV
PP- i*9 ff.)