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Old December 30th, 2017, 07:06 AM   #1
Patrick Weiler
Join Date: May 2008
Posts: 21
Default Moths and Carpet Beetles (Ringo is now a knight, btw)

The Little Buggers,

I was reading up on how to kill moths and carpet beetles and found a couple of references which may be helpful. I always thought putting a small bag or rug into a plastic bag and popping it into the freezer for a week would work, and a lot of web sites suggest just this thing. But, I have also heard it kills moths but not the eggs. One site says: "Placing infested items in the freezer (at about 5 F) may take weeks to kill the pests inside them. Cold storage freezers (at about -20 F) can eliminate pests in two to seven days, depending on the size of the item. Items to be frozen should be sealed in plastic bags with the air removed to help prevent frost damage." But, nothing about eggs. Here is that site, with lots of X-rated photos of carpet beetles and moths, and their larvae:


The site must be up to date, because at the bottom it says "Last updated February 4, 2109"

So, I continued my search and found what is probably an effective method for disposing of moths, larvae, pupae, eggs and anything else alive!

"A word of caution to any who plan to use cold as a moth/larvae killer.
(We were just having this same discussion on Knit-L). Cold, even relatively severe, DOES NOT KILL THE LITTLE BUGGERS. Here's the deal. Anything below freezing will keep any eggs dormant, ie., the larvae will not hatch and begin munching your beloved fibres. If you wish to KILL the buggies, subject your fibres/fabric to a six or seven-fold cycle of deep freeze (<10F/-12C) and then hot/humid (next to the shower-above 70F/whatever that is in C., I'm too tired to figure it out, sorry). The heat and humidity (think India/Burma/China) make the dormant eggs hatch, and then, when you pop the fabric back into the deep freeze, the cold kills the larvae. The larvae are the ONLY stage which are susceptible to cold. If they have pupated, then hand pick the chrysali (the larvae will have done their damage by this point-adult moths lack even mouth parts, and live a very short time). Even if you see chrysali (look like small grains of rice covered in, well, silk), subject the fibre to the heat/ cold treatment, for it's likely that there are unhatched eggs, as well.

Heat will also kill all the life stages, but as it requires constant temps above 170F for extended (25 minutes, to be sure) periods of time, most fabrics and fibres can't take it. (It's called stifling, and is what commercial silk growers do to all but the breeders of the silk crop before the chrysali are reeled).

In general, each of the heat/cold periods mentioned above, need to be of at least 48 hours of duration, but not more than 72, or you may just be feeding a generation of hungry larvae, yuk!
P.S. Among naptha's (mothballs) more darling side effects are liver/kidney damage, Parkinson's like tremors, permanant brain neurotransmitter dysfunction, birth defects (severe), convulsions and, occasionally, death. Read the warning label on the box sometime-charming stuff."

Well, this is beginning to sound evil, murderous and successful! But not quite enough on heating. So, here is another method which I had not heard about. The method I had previously read about was to use a clothes dryer. This one sounds much more effective:

"When I brought home my felt samples that were possibly exposed to moth eggs, I decided to try treating them with heat, since I could cycle through everything I needed to treat in a day, rather than over weeks if I used the freezer. Lisa recommends temps over 120° F for at least 30 minutes. Washing in water over that temp also works, but I decided I’d rather keep the wool dry so that I could store it right away. I’ve also steamed small amounts of yarn above boiling water, the way you would a vegetable, and that should work as well, as long as the heat penetrates to the middle of whatever you’re steaming.
I did put a pan of hot water on the lowest oven rack, so that the heat I was exposing the wool to wouldn’t be completely dry. The lowest temperature my oven will set at is 170° F, and I went for 200° just for good measure. I put an old towel directly on the middle oven rack, and put the wool items, not too many at a time so that the heat had a chance to penetrate, on top of that, and set the timer for 40 minutes before taking them out and putting in the next batch. At the end, the only thing that showed any signs of scorching was where the towel touched the sides of the oven, so I suggest folding your towel so that it doesn’t touch the oven walls. I keep a baking stone on the top rack of my oven, and I left it there to hold heat. If you wanted to, I think you could also do two racks of wool at a time, as long as you allow time for the oven to heat back up after you load everything in."

Now you should be adequately protected against the evil scourge, at least until another moth flies into your house, or a carpet beetle saunters in for a snack.

Patrick Weiler
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Old December 30th, 2017, 07:43 AM   #2
Joel Greifinger
Join Date: May 2008
Location: Massachusetts
Posts: 43
Default Carbon dioxide

Hi Pat,

One alternative to both chemicals and freezing/heating that I have contemplated but haven't tried is carbon dioxide treatment in a sealed, tent-sized bubble. Here is the description from a group that offers the service:

"One such method is using carbon dioxide gas in an impermeable, plastic bubble, known as a modified or controlled atmosphere treatment. Carbon dioxide gas is used to displace the oxygen in the bubble to a percentage (60-80% CO2) low enough to kill all stages of the insect life-cycle: adults, larvae, pupae, and eggs. Unlike alternative methods of treatment like freezing, the use of carbon dioxide is safe for all types of museum objects because it does not expose them to extreme changes in temperature and relative humidity. The residual air still contains its water vapor; thus, one third of the original humidity is maintained."

I'd be very interested in hearing about the experiences of any textile collectors who have tried this.

Joel Greifinger
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Old December 30th, 2017, 01:34 PM   #3
Steve Price
Join Date: May 2008
Posts: 99

Cycles of freezing and thawing are likely to be much more effective than just freezing one time. The cause of death in freezing is the formation of ice crystals and the expansion of water as it thaws, both of which contribute to rupturing cell membranes.

There's also a spray product called Sla that I've used for years on the advice of Saul Barodofsky.

Steve Price
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Old January 5th, 2018, 07:10 PM   #4
Lloyd Kannenberg
Join Date: Jul 2009
Posts: 10

Hello All,

I think Sla uses a chemical related to pyrethrin (not sure about the spelling), which is the active ingredient in a spray called Ultracide that I've used successfully for some time. It requires two applications about four months apart, the first to kill the active bugs, the second to kill those that hatched from eggs after the first application.

Lloyd Kannenberg
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