Series editors' preface - Wood Tools

352 Conservation of Furniture
may also promote tendering reactions caused
by light.
Biodeterioration
The major insect pests of textiles are carpet
beetles and clothes moths which attack mainly
wool, silk and other proteinaceous materials.
Cotton materials are not normally at risk of
attack by carpet beetles or clothes moths.
Several species of the family Dermestidae
are widespread in museums and may cause
serious damage to proteinaceous materials
such as silk, wool and leather used in upholstery.
The most common species of carpet
beetle is the variegated carpet beetle
(Anthrenus verbasci) but others such as the
Guernsey carpet beetle (Anthrenus sarnicus)
are similar in habits and appearance. Damage
to textiles is caused by the short, fat hairy
larvae of these insects, which are often
referred to as ‘woolly bear’. The larvae rapidly
destroy proteinaceous textiles, fur and feathers
and develop by a series of larval moults,
leaving behind their empty cast skins which
frequently provide the first sign of an attack.
Six to eight moults is normal but in adverse
conditions the number of moults may be much
higher. The insect pupates in the last larval
skin which is left behind when the adult
emerges. These large moults may be found in
places which are some distance from infestation
centres because the larvae have moved
away to find a safe pupation site. Because
carpet beetle larvae are small and can exist on
dust, hair, fibres from clothing and dead
insects, they do not normally have to move far
for food. However, larvae are highly mobile,
gaining access through cracks and crevices to
store rooms, display cases and other vulnerable
areas containing food sources to which
they are attracted. Within a major infestation,
larvae may be found at several different developmental
stages. A characteristic of new local
infestations is the predominance of small
larvae. Anthrenus spp. are able to tolerate
humidities as low as 20%–30%. The small
round adult beetle are 2–3 mm long and have
patterned markings of grey and gold. Adult
beetles are phototropic and are attracted to
short wavelength ultra violet radiation. They
fly from the safety of a dark area where
pupation has taken place towards the light in
order to leave the building to mate. Thus
adults may be found on window sills, particularly
of north facing windows, during peak
emergence months of June, July and August.
Mating frequently occurs on flowers
(especially Spirea spp.) and adult females then
re-enter the building through chimneys, air
vents and cracks to lay their eggs. However,
adults do not always have to leave the building
to mate and it is thus possible for an infestation
to become established and spread
despite meticulous sealing of entry and exit
points. Eggs are laid in dark crevices, usually
close to a food source for the newly emerging
larvae. Breeding reservoirs inside buildings
are usually associated with poor hygiene,
although objects may also become breeding
reservoirs. Birds nests, feathers, bird droppings
and broken birds’ eggs provide a rich source
of food for larvae and are typical external
reservoirs. For further information on carpet
beetle and its control see Blyth (1997), Hillyer
and Blyth (1992), Tímár-Balázsy and Eastop
(1998).
Several species of clothes moth attack and
damage textiles of which the webbing clothes
moth (Tineola bissellielia) and the case bearing
clothes moth (Tinea pellionella) are the most
common. Clothes moths prefer vitamin B,
sulphur and salts found in sweat and urine
and are attracted to dark humid, dirty
surroundings and soiled and degraded
proteinaceous materials, particularly wool
based textiles which are rich in sulphur
containing amino acids. The adults are small
dull grey-brown moths which scuttle around
rather than fly and which fold their wings
along their backs when at rest. Eggs may be
laid on fur, feathers, wool, or soiled silk. The
complete life cycle generally takes a year but
may be shorter under favourable conditions.
The case bearing clothes moth spins an open
fronted silk case around itself which it then
carries with it as it moves across the textile,
leaving a trail of partially eaten material and
fragments of excreta or frass. The larva moults
within the case and on maturity pupates
before emerging as the adult moth. The
webbing clothes moth also spins silk but
produces a sheet or tunnel of silk under which
it feeds on the textiles surface. Damage from
this source is evident by the large amount of
silk webbing and frass present. Adult moths
can fly in from outside and birds’ nests under