Carpet Beetles

Carpet beetles are a fairly common pest.  We continue to receive many calls us about this insect and we see an upward trend in their appearance in homes and businesses.  Though these insects will do damage to fabric, they known to be a pest in food products as well.  Carpet beetles occur naturally outdoors and then make their way into buildings.  They may enter through improperly sealed or improperly screened doors and windows or through other cracks or crevices, but due to their small size, sealing them out is completely is difficult.


There are two groups of Carpet beetles: the Black Carpet Beetles and Varied, Common and Furniture Carpet Beetles.   The adult Black Carpet Beetle, is black in color and oblong shaped and ranges in size from 1/8" up to 3/16" in length.  The other three, though about the same size, will have a variety of different wing color patterns and are somewhat more oval in shape.    Carpet beetles go through complete metamorphosis which includes egg, larvae (crawling stage), pupae (cocoon) and adult (beetle).   

Larvae of the Black Carpet Beetles are fairly distinctive.  They are quite hairy and are striped tan and white in color.   There may be tail bristles (hairs) visible at the back of the insect as well.  Inspection commonly reveals either live larvae or sometimes cast skins of the larvae.  It is this stage of the insect that actually ingests the fabric or other food.

Finding Evidence

Carpet beetle larvae may damage carpeting, clothing, hair, fur and animal hides.  They will also feed on the fur left on animal carcasses such as from mice, rats or squirrels that may have died inside of a wall, below a floor or in the ceiling or in an attic.  As stated above, they may also be found in food products including milled products such as pastas, cereals, nuts, etc..  Most homeowners spot the larvae or beetles crawling along a surface somewhere.  They may wander into areas away from where they feed.  They will chew irregular holes in fabrics including wool carpeting, but often feed on the nap of the fabric without eating the base threads. 

A common food source for carpet beetles is pet hair.  In areas around or behind furniture, accumulation of hair may provide ample food for this pest.  

Although one may find beetles as well as larvae,  we frequently see larvae brought to us as specimens.  Eggs are small and hard to spot and cocoons (pupae) are rarely noticed as they tend to blend in with the fabric.  Beetles can fly and are frequently found near windows because they are attracted to light.

Dealing with the Problem

These insect may be difficult to control.  You can discard affected garments or fabrics or have them dry cleaned as needed.   If a significant number of garments have been affected, ask the dry cleaner about a bulk rate.  Removal of pet hair or fur regularly with thorough vacuuming is helpful in reducing possible food sources for the larvae.  Removing clutter from floors will also help.  Carpeting may be dry cleaned as well.  You may want to dispose of the vacuum bag or empty the cup afterward as a precaution.  Yet another alternative would be to place items in a dryer on the high heat setting for 20 to 30 minute on high where practical.

Vulnerable clothing made of wool, cashmere, silks or leather may be stored in air tight plastic tote containers to help protect them from the beetles.

To control both the larvae and/or adults (beetles), a residual insecticide such as Permacide P-1 may be applied as a pin stream (jet) to baseboards and along the carpet backing up to six inches from the edge of the carpet using a coarse fan spray.   Wall to wall carpeting will need to be pulled off of the tackless strips in order to treat the backing.  Also, treat using the pin stream around both sides of the tackless strip itself to control any insects which may be hiding in that area.  Finally, treat any other moldings such as around window frames and door frames.

Other treatment areas include dressers or night tables.  Apply the spray inside around corners where the larvae may hide as well as the inside corners of drawers and the bottom of drawers where gaps are present.  Inside closets, treat corners including around window and door frame moldings and gaps alongside and above and below shelving.

To help eliminate the problem permanently, monthly applications of Permacide P-1 may be needed.   Consider one or two follow up treatment after 30 days based the level of activity.

Two newer products are available for the control of carpet beetles and their larvae: Bedlam Plus and Alpine Dust Insecticide.  Bedlam Plus is an effective insecticide for use in cracks and crevice to help kill insects hiding there while Alpine Dust Insecticide can be used to treat larger cracks and crevices very effectively because it spreads out well in such areas.   Dust insecticide may be an issue for some sites because it remains visible after application.   Careful cleanup of excess with a damp paper towel afterwards can minimize this problem.

In addition to the residual spray and insecticide dust, we offer Gentrol IGR Concentrate as the least toxic approach for helping to control this insect.  An IGR is an Insect Growth Regulator. This product will affect carpet beetles in two ways.   First, it works against the larval stage so that when affected larvae enter the pupae stage of development, their growth stops and they do not emerge as adults.  The second effect is the sterilization of the adult female which also helps to break the life cycle.   This product has a very low level of toxicity and does not affect people in the same ways that it affects insects.  The product is sold in a concentrate in a one ounce bottle that will make one finished gallon.  Note that IGR products are for long term control and will not impact insect populations immediately.

Gentrol may continue to be effective for up to four months so that frequent reapplication is not required.  Gentrol may either be diluted in water in a sprayer separately or it may be combined with the Permacide P-1 product to simplify the application, but once diluted it should be used within 48 hours.  It is possible to dilute smaller amounts of the Gentrol separately to stretch out the use of the product over a longer period of time.


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