Beetles
Insects which fly and lay their eggs in the pores and cracks in
wood. The larva causes the most serious damage, by burrowing internal
galleries in the installed material. They are present throughout
Europe, but attacks vary greatly depending on the geographic area.
The most important are Hylotrupes bajulus, Anobium punctatum and
Lyctus brunneus. There are many other insects of less importance,
which destroy the wood; among which, for example, are Hesperophanes
and Xestobium rufovillosum.
Hylotrupes bajulus (House Longhorn): is undoubtedly
one of the worst enemies of installed wood, in particular conifers,
and the damage caused by the larva is very serious. It is present
up to an altitude of about 2,000-m, not so widespread in the North
and Northwest of Europe. The vitality of this insect depends on
the temperature and humidity of the air. The incubation period
for the eggs may be 5 to 9 days at a temperature of 31.5°C
and a humidity level of 90 to 95% or 48 days at a temperature
of 16.6°C and environmental humidity at 18% (the latter condition
being very unfavourable). The larvae burrow galleries in particular
in the alburnum which become full of gnawed waste causing serious
structural damage to the wood which can lose all its structure
and solidity.
Anobium punctatum (Furniture woodworm): is
particularly widespread in maritime climates and wherever there
is high humidity. It attacks in particular timber or installed
wood of conifers or hardwood indifferently, affecting the alburnum
and the duramen. The larvae burrow galleries with coarse gnawed
waste mixed with excrement. Even if heavily attacked the wood
does not completely lose its resistance and the structure remains
recognisable.
Xestobium rufovillosum (Death-watch beetle):
attacks preferably timber or already installed wood, of various
hardwoods (Oak, Elm, Walnut, Ontano, Poplar) but which is fairly
humid, or old lopped decaying willow trees. The damage caused
by Xestobium is the same as the damage caused by Anobium. Its
importance is felt in particular in the structures in old buildings
throughout most of Europe.
Lyctus brunneus (Lyctus): in the past it was
given little importance, but the damage it causes in installed
casings and furniture is at present considered very serious. The
larvae which breeds at its best in very humid wood, attacks all
indigenous Hardwood with soft wood and with large vessels, plus
the alburnum of the hard species, in particular Oak. The only
species that seems to be immune are Popular, Beech and Birch,
whereas the Eucalyptus trees are very vulnerable. If the infestation
is particularly strong, the whole mass of wood is transformed
into a solid compressed gnawed waste where the structure of the
texture is no longer recognisable. The Lyctus brunneus is the
most common in Italy.
Hesperophanes sp.p.: a species common to Central
and South Europe. The wood that suffers most is: Cerro, Robinia,
Beech, Popular, Walnut and Chestnut. The females usually lay their
eggs in the nooks and cracks of installed wood such as framework
for roofs, furniture, wooden floors and all types of frames. The
damage caused by the larvae can be very serious because it involves
the structure and mechanical resistance of the part without any
possibility of repairing. It is also very difficult to diagnose.
Termites
Social insects divided up into various families. The most dangerous
species for buildings are those which live underground, mainly
Reticulitermes lucifugus and Reticulitermes santonensis.
In Europe termites can be found only in certain limited geographical
areas; they are present in Italy throughout the whole peninsula
and on the islands. In these areas, the use of wood preservants
in the fight against termites is integrated by the use of other
protective means, for example for floors, for foundation work
and walls. The danger of the attacks stems from the fact that,
as their activity is hidden from the light, a superficial inspection
will not reveal their presence. They always respect the external
surface of the pieces of wood so that the alarm (always to late)
is given by some beam or frame collapsing. The infection is by
this time widespread.