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The Museum Conservation Institute- Taking Care


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Insects and Wool Textiles

  • Characteristics
    In North America, the casemaking clothes moth, the common clothes moth, the varied carpet beetle, the common carpet beetle, the hide beetle and the harder beetle can all be found.
    The life cycle of these insects may be divided into four stages: the egg, the larva, the pupa, and the adult moth or beetle.  For the clothes moth, the larval stage will last between two months (a warm humid climate) and six months (a cool climate).  These are cream colored oblong caterpillars.  The larvae of carpet beetles eat for at least three-quarters of a year.  These beetle larvae have the shape of small red-brown caterpillars with numerous fuzzy bristles; they moult several times before reaching maturity.
    *** The larvae of these moths and beetles will attack hair, horn, feathers, wool, mounted insects (like butterflies), mounted birds, mounted animals, furs, horsehair stuffing in upholstery, wool batting in quilts.  Laboratory beetle specimens are fed dog food, but can survive on the dust of (wool) clothes and hair and dead insects in rooms that are not maintained.  The larval stages of all these insects prefer a dark, undisturbed environment at room temperature (77°F) and about 50-70% relative humidity.
    *** Adult carpet beetles, the size of a freckle and resembling ladybugs, seek light and flowers.  They can be found on the window sills in infested rooms.  Adult carpet beetles feed on the pollen and nectar of blooming Spirea, asters, dahlias, daisies, sunflowers, Virburnum, Caeothus, goldenrod, and the flowers of wild and cultivated fruits.  The bugs can enter a home with these flowers and blossoms.

  • Infestation
    Isolate the infestation by sealing the item (and even its tissue paper and container) in plastic bags.  Label the contents of the bag.  Do not gratuitously remove suspected items to other (probably uncontaminated) areas of the home.  Wear cotton or synthetic fabrics while working upon the infested objects.  Remove this clothing and wash it without exposing other areas of the home.  All objects that are definitely affected - that show signs of insect damage should be sorted by the remedial possible: a) washing (wet-cleaning), b) dry-cleaning, and c) other: fumigation with sulfuryl fluoride, flash freezing, fumigation with non-oxygen environments.
    Fumigation should be carried out by an experienced fumigator: the chemicals are deadly to humans as well as insects.  Flash freezing followed by prolonged exposure to sub-zero temperatures reduces the flexibility of the fibers to the point of embrittlement.  Special handling precautions are required.  Composite objects (made of more than one type of material) will react differently to changes in temperatures.
    Once the objects have been set aside and evaluated, the area itself must be treated to rigorous housekeeping: washing of walls and floors, especially cracks and crevices, washing of all drawers and cabinets (including the interior housing spaces upon which the drawers are placed).  The use of insecticides alone is not a satisfactory remedy.  Your County Agricultural Extension Service will provide additional housekeeping procedures.

  • Prevention
    Thorough housekeeping with rigorous spring and fall cleanings of all areas of the home are recommended.  Frequent vacuuming of carpets, restricted access and careful grooming of pets are suggested.  The sand-grain size eggs of carpet beetles can be easily removed by vacuuming; those of clothes moths require more effort as there is an adhesive on the outer layer.  Clothes soiled with human urine, perspiration, tomato juice, milk, beer, black coffee, or beef gravy are favored by the clothes moth larvae.  Cholesterol (in perspiration/ring around the collar) and yeast on brushed wool (flannel) is the preferred diet for clothes moths.  Furniture carpet beetle larvae are partial to beer and tomato juice stained woolens; black carpet beetle larvae do not show any preference.  Remember that part of the purpose of housecleaning is to inspect all the objects in the home, even the heirlooms and museum quality objects.  Inspections of all areas and objects should be part of the fall and spring projects.

  • Cautionary Notes
    Drycleaning is said to kill the larvae of clothes moths and that clothes moths cannot live on a diet of clean wool.  Mothproofing will impart a residual protection against moths and beetles.  Neither dry-cleaning nor washing nor mothproofing will prevent a voracious group of insects from at least attempting to feed upon your neglected objects. 
    There are two forms of mothballs: Naphthalene acts as a repellent.  Paradichlorobenzene (PBD) acts as a larvacide.  Both are known animal carcinogens and possible human carcinogens. For safety, susceptible garments and furnishings stored with small quantities (about 3 1/2 oz. of PDB for every 21 cubic feet of container) must be sealed against out-gassing: use footlockers, galvanized tins or other containers from which fumes cannot leach. Plastics may be sofened by mothballs. If mothballs can be smelled, they are not remaining in the container; odors are a potential harm to humans. To remove the smell safely, air garments out of doors: heat and breeze will evaporate the odor.
    Fumigation will kill adults and larvae; it should kill all eggs but a second fumigation after a 20-30 day incubation period is prudent for a severely infested object. 
    Vacuuming or brushing is the suggested first step to removing eggs and residues from textiles.  However, the brush or nozzle of the vacuum must be washed (with warm water and dishwashing liquid) and dried between objects or object groups so as not to spread the infestation.

Toxicity of Mothballs and Mothflakes (a) All conditions are assumed to be 25° Centigrade: both compounds will be more volatile and more concentrated at higher temperatures.

Chemical,
CAS
Registry Number

TLV
(ACGIH)
in ppm (inhalation)

PEL
(OSHA)
in ppm (inhalation)

Acute toxicity (inhalation)

Threshold perceptible odor

Human Low Lethal Dose (oral)

Other

Naphthalene
#91-20-3

10

10

2500mg/m3
(Life threat) = 477 ppm

0.084 ppm

30-100 mg/kg, i.e. 5-15 g = lethal

Known animal carcinogen; reasonably anticipated human carcinogen. Skin absorption also a major route of exposure; eye & respiratory irritant

Paradichloro-benzene
1,4 dichloro-benzene
#106-46-7

10

75

6000mg/m3
(Life threat) = 998 ppm

0.18 ppm

220-860 mg/kg

Known animal carcinogen; possible human carcinogen. Skin & eye irritant; renal toxicity

(a) Sources include: Olkowski, W. and H. Olkowski, "Clothes Moths...How to Protect Your Woolens" Common Sense Pest Control, 17 #1 (Winter, 2001): 9; MSDS Enoz Old Fashioned Moth Balls, Willert Home Products, St. Louis (1994) and MSDS Enoz Moth-Ice Crystals, Willert Home Products, St. Louis (1994); 2001 TLVs ® and BEIs ®, Cincinnati, Ohio: American Conference of Governmental Industrial Hygenists, 2001.

* For further information on possible treatments of textiles or costumes, please consult a textile or costume conservator.

Updated: September 2006

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