Moth Control

My wife’s aunt – an otherwise courageous woman - is deathly afraid of moths above all other insects. Moths don’t bite, sting, suck blood, inject venom, or inflict pain of any kind. They don’t creep like spiders or buzz like flies or bees. Thusly, I have decided it is good and just to ostracize this aunt. Her fear of moths is irrational. However, I don’t find it irrational to hate, loathe, or be disgusted by moth behavior.

Moths, as indoor pests, fall into two categories: moths that infest fabrics and moths that infest stored foods. The webbing clothes moth, casemaking clothes moth, and brown house moth are common fabric moths. They are part of a very small group of creatures that can digest keratin – the protein which makes up animal hair. The Indian meal moth, Angoumois grain moth, and Mediterranean flour moth are common moth villains in the pantry, where they will ruin just about anything. Some moths, like the brown house moth and white-shouldered moth, are happy to consume both woolen heirlooms and your retriever’s kibble. Don’t fear these moths like my eccentric in-law. Moth control is easily accomplished even by homeowners with little experience with pests. Below you’ll find safe, effective ways to combat both fabric and pantry moths.

Behavioral Control: Storage and care for moth control

Proper storage and care of moth-susceptible fabrics. What do fabric moths eat? Anything of animal origin – mostly woolens (and synthetics that contain wool), but they’ll damage silk, cashmere, and cotton too. But the damage and despair caused by clothes moths can almost always be avoided. Here are some ways to keep your precious fabrics safe from the silent-winged menace.

1. Adult moths don’t eat fabrics – they just fly around looking for sex and nice woolens to lay eggs on. The larvae that do the eating and destroying are quite fragile; this is why moths rarely harm often-used items. If you’re not going to wear or use an item, store it properly (below). Or, if you want it on display, air it out and brush or beat it outside twice monthly, just like grandma used to do. This will dislodge most moth larvae and eggs.
2. Moth larvae need more than animal hair to mature, mate, and lay eggs. Dead skin, sweat, urine (accidents happen), as well as food and beverage stains supply moth larvae with the nourishment they need to thrive. As a result, clean fabrics are less attractive food sources and won’t always produce successive generations of moths. Keep your fabrics clean to avoid moth damage. Ironing also kills moth larvae, eggs, and pupae on fabrics.
3. Storing susceptible fabrics and furs requires a sound, impenetrable barrier. You can store items in boxes or even heavy duty plastic garbage bags. Just be sure to seal off openings with heat (for plastic) or tape. Large plastic containers that seal for storage under beds work as well. For extra protection, wrap items in heavy craft paper and seal with tape. Natural moth repellents like cedar, camphor, or lavender (see Biological Control) can be sealed inside for extra protection. If you store items with a repellent or fumigant, air out and wash them before wearing or displaying.

Proper storage of foods to avoid moth problems. Pantry foods (including pet food) cannot be infested by moths when stored in strong containers with tight-fitting lids. Whole aisles in big box stores are dedicated to such containers, but be sure they seal air tight. Glass jars that seal with clamps and rubber gaskets are particularly effective. If you use screw-top jars, be sure they have rubber seals, as jars without rubber seals can be invaded by moth larvae and other pests - they skillfully sneak through the threads. This feat perfectly illustrates how small a space moths need to invade food. They can also chew and worm their way into plastic bags, paper, cardboard, etc.

If you find that food has become infested, investigate the scope of the problem and deal with it promptly. Chances are, the moth larvae you’ve run into were brought into your home with a food item (avoid purchasing rice, nuts, and grains from bulk bins), but they may have spread. Investigate all food items as well as food storage and preparation areas. Webbing and frass (insect excrement, looks like colored sand) are telltale signs of moth larvae activity. All infected items should be discarded carefully. You can either bury, burn, or seal items in plastic before tossing. If your moth problems are severe, you’re better off throwing everything they could possibly contaminate.

If an item appears to be unmolested by the moths but you need absolute assurance, wrap the item in plastic, seal it with tape, and place it in the freezer for four days. Some people, having dealt with pantry moths in the past, freeze food items upon purchase or store items in the freezer until needed. Freezing will ensure all moth larvae, pupae, and eggs have been destroyed. Once you’ve discarded infested foods, clean all food storage areas (or offending areas) and food containers with soap and water. Be sure to get into all cracks and crevices, and vacuum thoroughly.

Habitat Control: The importance of humidity and sanitation for moth control

Control humidity to control moths. Whether you’re dealing with fabric or food moths, maintaining a low relative humidity is essential for control. When humidity is high, moths eat, develop, and reproduce more quickly. Using an air conditioner or dehumidifier will do the job in most homes. You must keep relative humidity below 70% to avoid shaming your family. Maintaining 55% is ideal and very hard on moths. You can monitor humidity levels in sensitive areas with the use of a hydrometer, which can be purchased at any hardware store.

Cleaning, and especially vacuuming, is key to moth control and prevention. Keeping a clean home is important for both fabric and food moth control. Moth larvae will eat food particles and crumbs, clumps of pet hair, human hair, dead insects, lint, and other filth. Vacuuming often (using a machine with a HEPA filter) will remove such food sources, and it will remove moth larvae, eggs, and pupae from fabrics, cracks, and crevices. Areas of importance include underneath furniture, along walls, dark and secluded (or unused) areas, carpets (especially perimeter), rugs, drapes, ducts, vents, closets, drawers, shelving, and around windows and doors. When cleaning, keep an eye out for places moths and other pests may be using to get into your home.

Investigate your home for animal nests. Both food and clothes moth infestations can get their start with bird or rodent nests. The moths feed on the feathers, fur, or dried remains of these creatures. Food moths will sometimes spread from the food (nuts, seeds, grains) brought in by such pests. Where to look? Crawl spaces, attics, chimneys, basements, and any dark secluded areas are a good bet.

Physical Controls: Moth control through exclusion

Pest proof your home. Yes, moths are often brought into homes via infested food and clothing or other pests; however, they also trespass using weaknesses around our homes. Apply weather stripping around doors and windows, fix screens with screen patches or silicone caulk, and install door sweeps.

Seal off harborages (cracks and crevices) around moth-infested areas. Moths and their larvae – like many pests – avoid our wrath by hiding in cracks and crevices in our homes. If you take away these hiding spots (caulk and caulking gun, putty, or foam), you lower your home’s moth population potential. In the kitchen, seal off cracks and crevices formed by cabinets, drawers, trim and baseboards. If possible, seal off any places food crumbs tend to accumulate. In closets and anywhere fabrics and furs are kept, seal off cracks in floors, walls, shelving, trim, baseboards, and so forth. Many pest control firms will apply insecticidal dusts or diatomaceous earth to cracks and crevices before sealing them off (see Biological and Chemical Controls).

Mechanical control: Kill moths with heat and cold

Using temperature extremes to control fabric moths. Killing fabric moths in cold blood with the use of cold is easy and fun. Place smaller garments in a plastic bag and remove as much air as you can before sealing it. Place the garment in a freezer for four days to kill moths and larvae. Be sure to let the item warm up before removing the plastic to avoid damage. If you live in the wretched North, as I do, you can bring items large and small outside on cold days (0°F) for a few hours to attain control.

If you’ve treated all clothing in an enclosed space – a closet or small room – you can use heat to make sure all moth larvae, eggs, and pupae are dead. You’ll need a space heater, thermometer, and timer. Keeping a space at 105°F to 107°F for four sustained hours will kill moths at all stages. The practice of using temperature extremes to combat pest infestations is becoming a more and more common service offered by pest control companies. The public is pesticide-weary and ready for safer, greener alternatives.

Biological Control: Moth traps and natural moth control

Make your own moth trap. Moth traps are an important part of moth control. They are used to both monitor (see if what you’ve done so far is working, detect infestations) and control moths. Plain, cheap sticky traps for flies, insects, or rodents can be used alone or with bait attractants. For pantry moths, impregnate sticky traps with the foods they’ve been after and place strategically throughout food storage areas. Another option for pantry moths is mixing 1 part boric acid (Borax) with 3 parts cornmeal and placing small amounts on jar lids around stored foods.

To make clothes moth traps, start with flypaper, white fly traps, or box sticky traps. Place one or two cotton balls soaked in fish oil (from tuna, sardines, etc) on the sticky traps and hang them from the ceiling. Floor traps should be placed along walls and in corners. Two to three traps is plenty for most closets.

Buy commercial pheromone moth traps for both fabric and pantry moths. More and more pheromone traps have become available for clothes and pantry moths in recent years. They are effective, non-toxic, and perfect for homeowners and business owners alike. You can buy pheromone moth traps from numerous online vendors. The ProPest Pheronet Pantry Pest Trap, ProPest Clothes Moth Trap, Safer Brand Moth Traps, and EnviroSafe Moth Traps are all highly recommended, but it all depends on your situation. The pheromones in certain products will be better at attracting specific species of moth than the pheromones in other products. That’s why one review of a product will read “Big time rip-off, don’t waste your money” and another will read “This product solved my moth problem and saved my marriage.” The first reviewer may have been dealing with a type of moth not listed on the label. Many online vendors, wise to this fact, sell 3-4 different pheromone traps in one package, which is the smart choice if you’re not sure which species you’re dealing with.

Pick a moth trap for your situation and give it time to work. If it only catches moths when you run around the house cursing and crushing moths with it, it’s time to switch traps.

Apply food-grade diatomaceous earth to cracks and crevices. Diatomaceous earth is an all-natural desiccant dust. In the reduced-scale world of insects, this stuff is like broken glass. Adult moths and larvae alike walk over the dust, begin leaking fluid, and die in agony. Apply a thin layer of DE inside cracks and crevices around food or clothing areas. A thin layer on shelving and in drawers is also a good idea. You can usually find DE at gardening stores. If you’re looking online, Concern and MotherEarth D are two good options.

Use natural moth repellents. People use a variety of natural substances as moth repellents. The most popular moth repellent for fabrics is cedar, which is sealed in with stored fabrics and also placed in drawers and closets. You can buy cedar chips and blocks (from which the oil permeates as a vapor) at most big box stores. You can also buy plain cedar oil to create sachets. Camphor is another popular, effective fabric moth repellent. It can be purchased in ball, flake, or cake form Just be sure to air out and wash items after storage, as camphor is somewhat toxic. Other common repellents include dried lavender, lavender oil, and clove oil.

For pantry moths, spreading cloves, eucalyptus, bay leaves, and dried lemon peels near stored foods are all common practice. Researching moth repellents, I found countless recipes that mix a variety of natural ingredients; however, evidence for the efficacy of these repellents is anecdotal.

Chemical Control: Moth control with chemicals

Why is it so important to be extra careful when using commercial poisons to kill moths? Because moths infest sensitive materials that should never come into contact with insecticides – clothing and food. Careful, focused space treatments can aid in moth control, but they do not replace the sanitation, care, exclusion, traps, and other non-toxic methods of control.

Products recommended for moth control. Dust treatments are great for treating those areas in which moth adults and larvae seek shelter – cracks, crevices, underneath the edges of carpeting, trim, wall voids, and other protected areas. Diatomaceous earth (DE), being food grade, is great for food preparation areas. Borid Boric Acid Dust, Boric Acid Insecticidal Dust, Delta Dust Insecticide, and PyGanic 1% Pyrethrin Dust are all quality products. Here are some other options for controlling moths:

• There are many easy-to-use (aerosol can), residual sprays for controlling moths that perform the same function as dusts. Cy-Kick Aerosol, D-Force HPX, and Perma-Dust Boric Acid Dust Aerosol are good examples.
• Long-lasting microencapsulated products, such as Demand CS (Lambda-cyhalothrin 9.7%), are great for closets, dressers, wardrobes, and underneath furniture and rugs.
• Fumigation by an experienced pest control firm is an option for severe infestations. It achieves quick control of moths, but it’s expensive and supremely nasty.

Take care when using naphthalene and paradichlorobenzene (PDB), two common fumigant ingredients found in moth balls and moth crystals. These chemicals are often sealed in with stored fabrics to prevent moth damage. Neither of these chemicals is a moth repellent (though the stink repels humans); they are fumigants and will kill moths and moth larvae in enclosed spaces when vapors build up. However, toxic vapors aren’t just bad for moths; naphthalene is a known carcinogen that, when ingested or inhaled, kills red blood cells. PDB is also widely believed to be carcinogenic, and prolonged exposure can lead to liver and kidney damage as well as reproductive abnormalities.