July 28, 2011

Vintage Enemies 101: Silverfish

Pest damage is one of the most frequent problems we see in the vintage clothing business, though the clothes moth is not always the most common culprit. In hot, humid climates we find that silverfish are able to create much more damage.

The silverfish is a small, soft insect about 1/2 to 1-inch long, silvery-white to gray with a transparent look. They're carrot-shaped and wingless. Silverfish will feed directly on cotton, linen, silk and rayon, but they will also feed on stained areas of garments (regardless of the fiber itself) if the stain content includes a carbohydrate or protein food source. Starch is a common carbohydrate to find in clothing, and silverfish will feed on starched garments, which gives good reason to store clothing without starch or other finishes. Feeding leaves holes, usually with arc patterns in irregular shapes.

Silverfish are sneaky creatures. They are nocturnal and fast-moving, so it's often hard to spot them until they're either prolific, or their nesting place is uncovered. They prefer to live in dark places, and depending on the particular species, they may like cool or warm temperature, and humid or dry conditions. In general, low temperatures and a dry environment inhibits the growth of a population. A silverfish can live two to eight years, and an individual female can lay about 100 eggs in her lifetime. The eggs are not usually visible in an infestation, only live or dead adults are usually apparent. Because silverfish reproduce relatively slowly, an infestation becomes severe over years rather than months.

Silverfish will stay in an area once they locate a food source, which is often a bookshelf or pantry, or potentially your closet. An easy way to prevent silverfish is to check on your clothes in storage. Simply moving them from one location to another (even one side of the closet to another) can upset silverfish and deter them from making their home in your clothes. If you're not sure whether you have silverfish, try one of these two methods:

  • Make a flour card. Mix some flour with just enough water to make a smooth paste. Paint a thin coat of this mixture onto a plain piece of paper or cardboard, and lay it on the floor or a dark corner of your storage area. If silverfish are present, they will feed on the flour, leaving shallow ridged marks.
  • Make a trap jar. Put some dry flour into a glass jar, and apply a piece of masking tape to the outside from top to bottom. The masking tape will give a textured surface for the silverfish to climb up as it seeks out the flour food source. The silverfish will drop into the jar and wait for you to check the trap!

If you find silverfish in your clothes area, first check for damage to assess the extent of the problem. If there are several damaged garments, or you discover more than one or two silverfish in your evaluation, you should remove the garments, fumigate, and ideally have the clothes cleaned. If the cost is prohibitive, you can always freeze the garments for 72 hours to kill any live silverfish in the folds of the fabrics. This must be done in one large batch, in order to exterminate all the pests at once. Microwave ovens will also kill silverfish in 30-60 seconds

If a silverfish is seen but damage is minimal or non-existent, fumigation would be expedient but is not necessary. For this kind of occurrence, and for preventative maintenance, we recommend an inexpensive bait using boric acid. Boric acid is a powder that is toxic to silverfish by contact or ingestion. It's also toxic to people and pets, so read the bottle label carefully and clean up your work area well.

For the bait, thoroughly mix 1 tsp pure boric acid and 1 cup flour. Leave this powder in a small bowl with masking tape along the outside to give the silverfish a path into the bowl. Pure boric acid may also be brushed or puffed into corners of storage areas, into the edges of carpets and behind wall outlets, if the area is safe from children and pets.

It's not unusual to find a silverfish but no visible damage to your clothes. Silverfish can live without food for up to one year, but their presence alone is enough to warrant a careful inspection! With regular attention to your clothes storage, these common pests can be prevented or eliminated without difficulty.

--- April Ainsworth

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