Bugs are common in all our homes and in general they are a temporary nuisance in the home environment. However, within the museums, the consequences of an invasion take on much greater importance. Since we care for historic items, insect damage cannot be tolerated and we must be vigilant in tracking and taking preventative action. One way that museums do this is by setting up a monitoring program. A basic museum monitoring program consists of bug traps at specific locations, followed by identifying the catch to determine what the insects are. The following graph is tabulated from data taken from floor traps in the building. The graph illustrates the inside life cycle of the carpet beetle. It also dramatically shows when certain types of collections will be most at risk.

The reason for the collection of this information may not be immediately clear, but monitoring provides a clear way of measuring the effects of our bug control efforts. For example, if I have a large number of silverfish, I might wish to put on better door seals to keep them out. If I see a dramatic drop in the silverfish population level, I will know that this action has worked. If not, then I will consider other solutions. This is just one element in our program and how we protect historic objects. Monitoring in this way has become an invaluable tool in our insect control efforts and perhaps of some use within the home for those individuals wishing they had alternatives to fighting those critters without pesticides.

Silverfish

This bug will be familiar to most and perhaps one may have seen these little critters crawling around bathtubs. Silverfish crawl everywhere, in our basements, in our kitchens, and in our garages. These insects, while common, have very specific temperature and humidity requirements. They love warm temperatures and moist conditions which is why they love our houses.

They are also very simple yet remarkable creatures and have been around for a long time. Their origin may date back 400 million years and have been extremely adaptable like the cockroaches. As an example of their stamina, Silverfish can exist without food for many months.

There are many different species of Silverfish, but only a few species inhabit our houses. In the past, they probably existed in greater numbers in houses, but modern heating systems tend to dry out the air. However, silverfish still like our homes because they also love to feed on what we have.

They adore rolled oats, ground, or dry beef. They also like glue of all types, especially the paste behind wallpaper and bindings in books. In fact, they will eat gold lettering on book covers to get at the glue. They can be a problem if one has a library at home and certainly a problem for museums housing large book collections.

They feed on textiles like linen, silk, and especially on any materials that have been starched. On a strange side note, they also like certain synthetic fibers like Rayon.

Clothes Moth

However, a bigger pest of fabric in your house is the Clothes Moth.

Perhaps, a common misconception about Clothes Moths is that the adult stage also feeds on textiles. In fact, only the larval form of Clothes Moth feeds on the fibers. They are in fact, not attracted to the fibers directly, but to the stains on them. These stains provide the nutritional elements required for them to survive. Sweat, food, blood, and even urine are attractive. So often with moth damaged historic textiles, the only areas consumed, are the areas where a stain had existed.

Silken Cocoon Casing

One of the biggest difficulties with Clothes Moths are their accurate identification. There are many types of moths that resemble one another quite closely. Indeed, many species that resemble Clothes Moths are not pests of textiles but are attracted to stored food products.

The surest way of determining the possibility of Clothes Moths are finding their silken cocoon casings in the sweater drawer. However, they probably have hatched, consumed and left. Prevention is obviously the way to go but the first step is to always make sure that all stored clothing has been thoroughly cleaned.

One may be surprised to learn there other bugs that can inflict more damage on textiles than Clothes Moths. These insects are commonly called Carpet Beetles and the following picture is what they look like.

Carpet Beetle Graveyard

Carpet Beetles are without a doubt some of the most damaging insects to have in a museum. They are primarily pests of animal material and attack hides, feathers, silk, furs, and specimens like butterfly collections. They attack many textiles like cotton and wool. Like the Clothes Moth, they also prefer stained items, particularly those with animal based stains.

Although, these beetles prefer natural history items to feed upon, they are opportunists and will attack other items if preferred food sources are not available. They also have a larval stage and like the Clothes Moth, this is the stage where all of the damage occurs.

Carpet Beetle Larval Casing

There are many species of Carpet Beetles in the world, but the one pictured above is called the Varied Carpet Beetle. They are very pretty up close, but also very small. They are approximately a fourth of the size of the common Lady Bug. Consequently, their larval stage is equally tiny and difficult to see without knowing what to look for and where. One sign of a possible infestation is the larval casings left behind after either a molt or emergence into adulthood. The picture is an example of what this casing looks like.

Like the Clothes Moth, the Carpet Beetle may have long left the scene and only left a casing behind. In one example here at the museum, there was a Victorian shadow box containing a decorative floral piece made entirely out of human hair. This is a peculiar item but would be extremely attractive to Carpet Beetles. Thus, staff at this particular historic site became concerned when they observed the casings and sent the item here for examination. Upon inspection, no live larva or damage were detected. Perhaps a Carpet Beetle had lived there at the turn of the century?

The purpose of mentioning this specific item, is that damage can occur without being noticed. In this case, there was no infestation, but there could just as easily have been one. Carpet Beetles do not discriminate between museum artifacts or family heirlooms and irreplaceable treasures could be lost. Regular inspection for signs such as casings, will prevent extensive damage and control measures can be started.

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Last Updated: June 5, 1997
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