Museum collections are
vulnerable to destruction from pests such as insects, rodents, birds and mold.
This type of deterioration to collections is not always addressed because the
damage is often gradual, obscured from general view, and therefore, unnoticed.
Even though museum owners or executives are somehow aware of these possible
attacks, everyone thinks that it won't happen to them. However, over time this
persistent activity can have devastating effects on museum collections.
A pest in a museum
can cause far more damage than the same pest in a home or an office building.
Carpet beetles in a stuffed bear, clothes moths in a native Cyprus headdress, or
cigarette beetles in a herbarium can destroy irreplaceable artifacts. But while
museum specimens must be protected, their sensitivity to chemical and
environmental stresses means that standard pest control procedures are often
unacceptable. Liquid pesticides may stain certain materials, heat treatment can
damage paintings, dusts can abrade sensitive specimens. Caution is the byword in
museums.
"A little monitoring over a long time is
more effective than a lot of monitoring for a short time."
Each new pest
problem must be analyzed on its own. Before taking any actions to control a
pest, be sure that those actions will not themselves damage the museum's
collections. Although the use of pesticides may at times be necessary,
indiscriminate use or dependence on pesticides is unacceptable.
Any pest with chewing mouthparts is a risk to museum specimens. Carpet beetles,
clothes moths, powderpost beetles, cockroaches, termites (drywood &
subterranean) and others pose direct threats to specimens through feeding
damage, feces, and excretions. Some pests pose indirect risks such as fires
(rodents gnawing on wires) and secondary infestations (dead cluster flies in
attics can attract carpet beetles).
Pest Management
A pest management program begins with a
survey to identify the risks of the current situation. Consider the three means
by which museums control pests: the building and its surroundings,
portable fittings and hardware and staff activities and procedures.
In the survey, details of these three methods are evaluated or are noted for
their absence. A pest management program incorporates existing strengths and
lists specific improvements. The program must incorporate contributions of all
three means of control and must fairly represent the differences in scope, cost,
and effectiveness of each.
IDENTIFICATION AND BIOLOGY
Any pest that infests houses, restaurants, or other buildings may at some time
become a pest in a museum. Certain pests, however, repeatedly threaten museum
collections. They can loosely be grouped into five categories:
The first step in solving any pest problem is to identify the pest and learn
about its biology and habits. While it is impossible to discuss each pest in
detail in this manual, the brief discussions below may help you understand a
little about the habits of the pests most likely to infest museums or damage
museum specimens.
Fabric Pests
Most insect damage to fabrics is caused by Carpet Beetles (in the family Dermestidae) or clothes moths (in the family Tineidae)
& Silverfish. The adults stage is seen
most often seen since adults fly and some are attracted to lights and windows,
but it is not the adult insects that do the damage. They feed outside on pollen
or not at all. It is the larva or immature stage that feeds on fabric, fur,
feathers, or virtually anything made of animal fibers.
Carpet Beetles
Immature carpet beetles feed on dried animal products such as wool, silk, felt,
hair, fur, feathers, dead animals, and stuffed trophy heads. They do not feed on
synthetic fabrics, but sometimes damage wool-synthetic blends or synthetics
stained with urine, sweat, or food.
Carpet beetle larvae are repelled by light and are usually found burrowed deeply
into infested material or in little-used drawers, cases, and storage bins. To
grow, they molt and shed their skins. In heavy infestations, you may find large
numbers of these light-colored shed skins. The adults are often seen crawling up
walls and congregating on window ledges.
There are many species of carpet beetles. In addition, many common beetles
resemble carpet beetles. Be sure to get the pest beetle properly identified so
that you can zero in on the infested goods and likely harborage sites. Four
species of carpet beetle are most likely to be found in museums.
Black carpet beetle (Attagenus unicolor) is the most abundant and
destructive of the carpet beetles. The adult is 1/8"- 3/16" long, a solid dark
brown or dull black color, and more elongate than carpet beetles described
below. The larva is less than 1/4" long and carrot-shaped. It is covered with
golden brown hairs and has a characteristic "tail" of long hairs at the rear
end. Varied carpet beetle (Anthrenus verbasci) is primarily a
scavenger. It is common in the nests of birds, on dead animals, and in insect
collections, but can damage woolens, carpets, wall hangings, hides, horns, and
bone artifacts. Small populations often go unnoticed behind furniture or along
baseboards feeding on accumulated lint, hair, food crumbs, dead insects, and
other organic debris.
Common carpet beetle (Anthrenus scrophulariae) attacks carpets,
woolens, and animal products such as feathers, furs, leather, silks, mounted
museum specimens, and pressed plants.
Furniture carpet beetle (Anthrenus flavipes) attacks furniture
(particularly old horsehair-stuffed furniture) and items made from wool, fur,
feathers, silk, horns and tortoise shell. The larva is difficult to tell from the
common carpet beetle.
Clothes Moths
Small grain and flour-infesting moths
are often confused with clothes moths. However, clothes moths have different
flying habits. They avoid light and are rarely seen flying. They prefer dark
corners, closets, and storage areas, and usually remain out-of-sight.
The primary food of clothes moth larvae is soiled woolens, but they also feed on
silk, felt, fur, feathers, and hairs. In museums they often damage woolen
clothes (particularly old military uniforms), feather hats, dolls and toys,
bristle brushes, weavings, and wall hangings.
The webbing clothes moth (Tineola bisselliella) and the casemaking
clothes moth (Tinea pellionella) are the two most common clothes moths
found in museums. The larvae are small white caterpillars with brown heads. They
feed on the surface of the material infested. The webbing clothes moth produces
feeding tunnels of silk and patches of silken webbing on the fabric's surface.
The casemaking clothes moth is rarely seen since it constructs a cylindrical
case of fabric which it carries around to hide and feed in. The color of the
larva's case can help you locate infested materials.
Wood Pests
Materials made of wood are susceptible to attack by a number of wood- infesting
pests. The culprits in museums are usually powderpost beetles or drywood
termites. Both can severely damage valuable artifacts while remaining invisible
to the untrained eye.
Powderpost Beetles
These are a group of beetles in the insect families Anobiidae (anobiid,
furniture, and deathwatch beetles), Lyctidae (true powderpost beetles), and
Bostrichidae (false powderpost beetles). The term "powderpost" comes from the
fact that the larvae of these beetles feed on wood and, given enough time, can
reduce it to a mass of fine powder.
Powderpost beetles spend months or years inside the wood in the larval stage.
Their presence is only apparent when they emerge from the wood as adults,
leaving pin hole openings, often called "shot holes," behind and piles of
powdery frass below. Shot holes normally range in diameter from 1/32" to 1/8",
depending on the species of beetle. If wood conditions are right, female beetles
may lay their eggs and reinfest the wood, continuing the cycle for generations.
Heavily-infested wood becomes riddled with holes and galleries packed with a
dusty frass (wood that has passed through the digestive tract of the beetles).
Both hardwood and softwood can be attacked by powderpost beetles, although
lyctids only infest hardwoods.
Items in museums that can be infested by powderpost beetles include wooden
artifacts, frames, furniture, tool handles, gun stocks, books, toys, bamboo,
flooring, and structural timbers.
Drywood Termites
Unlike their cousins the subterranean termites, drywood termites establish
colonies in dry, sound wood with low levels of moisture, and they do not require
contact with the soil. They are primarily found in the coastal southern states,
California, and Hawaii, but they are easily transported to northern states in
lumber, furniture, and wooden artifacts.
Drywood termites attack wooden items of all kinds. The termites feed across the
grain of the wood, excavating chambers which are connected by small tunnels. The
galleries feel sandpaper-smooth. Dry, six-sided fecal pellets are found in piles
where they have been kicked out of the chambers. The pellets may also be found
in spider webs or in the galleries themselves.
A swarming flight of winged reproductive termites can occur anytime from spring
to fall. Most drywood termites swarm at night, often flying to lights.
Stored Product Pests
Many museums include items made in part of seeds, nuts, grains, spices, dried
fruits and vegetables, and other foods. A long list of pests, traditionally
called "stored product pests" or "pantry pests," can infest items containing
these foods. Probably the most common of such pests in museums are the cigarette
beetle and the drugstore beetle.
Cigarette Beetle (Lasioderma serricorne) is named for the fact
that it is a pest of stored tobacco, but is also a serious pest of flax, spices,
crude drugs, seeds, and, most importantly for museums, books and dried plants.
This beetle has been called the "herbarium beetle" because of the damage it can
cause to dried herbarium specimens. It has also been found infesting rodent
bait.
The adult beetle is light brown, 1/8" long, and the head is bent downward so
that the beetle has a distinctive "hump-backed" look. It is a good flier. The
small larva is grub-shaped and whitish, with long hairs that make it appear
"fuzzy." It has yellow- brown markings on the head.
Drugstore Beetle (Stegobium paniceum) feeds on a wide variety of
foods and spices (particularly paprika or red pepper). It is also a serious pest
of books and manuscripts, has been reported "feeding on a mummy," and has been
known to chew through tin foil and lead sheeting.
The adult beetle is very similar to the cigarette beetle. With careful
examination through a magnifying lens, the drugstore beetle may be distinguished
by its three- segmented antennal club. The larva, too, is similar, but does not
appear as "fuzzy."
Moisture Pests
Moisture is not only a threat to museum specimens on its own, it may attract a
number of moisture-loving pests that can do additional damage. The most
important of such pests are the molds and insects in the order Psocoptera that
feed on those molds.
Molds. Molds are fungi that can cause damage or disintegration of organic
matter. Basically plants without roots, stems, leaves, or chlorophyll, molds
occur nearly everywhere. When moisture and other environmental conditions are
right, molds can appear and cause significant damage to wood, textiles, books,
fabrics, insect specimens, and many other items in a collection. Their growth
can be rapid under the right conditions.
It is important to realize that fungal spores, basically the "seeds" of the
fungus, are practically everywhere. Whether molds attack suitable hosts in a
museum depends almost exclusively on one factor: moisture. When moisture becomes
a problem, molds will likely become a problem too.
Psocids. Although psocids are commonly called booklice, they are not
related to parasites such as head lice or body lice. Booklice got that name
because they often infest damp, moldy books. They feed on the mold growing on
paper and in the starchy glue in the binding. Psocids also infest such items as
dried plants in herbaria, insect collections, manuscripts, cardboard boxes, and
furniture stuffed with flax, hemp, jute, or Spanish moss.
Psocids do not themselves cause damage. They become pests simply by their
presence. However, their presence also indicates a moisture problem and the
likely presence of damaging molds. They are tiny insects, less than 1/8" long,
and range in color from clear to light grey or light brown. Most indoor psocids
are wingless, looking a bit like a tiny termite.
General Pests
Any household pest may become a pest in a museum. Cockroaches, rodents,
silverfish, ants, and other common pests can invade and infest a museum as well
as a house or other structure. The biology and ecology of these pests are
covered in detail in other modules of this Integrated Pest Management
Information Manual, and will not be repeated here.
Sanitation
Sanitation is a crucial factor in pest control. A clean,
uncluttered environment is not attractive to pests. The condition of the
building itself is another important factor in pest control. Pests infiltrate
through cracks and holes in building structures. It is important to seal
openings in buildings to inhibit passage. Pests are also brought into museums
from the outside on objects and sometimes people. Containment of affected areas
or objects is important in preventing infested materials from contaminating
non-infested collections.
Early detection is critical in pest management programs.
Regular inspection of the museum environment and collections is necessary to
control activities as they occur. Records should be kept for long term
evaluation of changes.
Ermones® Pest Management 
