Why Clothes Moths Seek Out Wool

The webbing clothes moth (Tineola bisselliella) and the case-bearing clothes moth (Tinea pellionella) are the two species most commonly encountered in Canadian homes. Neither species actually eats fabric — it is the larvae that cause damage by feeding on keratin, the protein found in animal-derived fibres including wool, cashmere, angora, alpaca, silk, and fur.

Adult moths are attracted to soiled fabric. Perspiration, food residues, and body oils make garments especially appealing as egg-laying sites. This is why thoroughly laundering or dry-cleaning woolens before storage is consistently the most effective preventive measure — regardless of what repellent is used afterward.

Tineola bisselliella — the common webbing clothes moth
Tineola bisselliella, the webbing clothes moth. Image: Wikimedia Commons (public domain)

How Cedar Works — and What It Cannot Do

Eastern red cedar (Juniperus virginiana), the species used in most cedar chests and closet liners sold in North America, releases volatile aromatic oils — primarily cedrol and thujopsene — that repel adult moths. Research indicates these compounds affect the olfactory receptors of insects, making the environment unpleasant. However, cedar oil does not kill larvae already established in a garment, and its concentration diminishes over time as the wood dries out.

Practical note: Cedar blocks lose much of their potency within two to three years. Light sanding with 120-grit sandpaper refreshes the surface and releases fresh oil. Alternatively, small amounts of cedar oil diluted in a carrier can be applied to older blocks.

Placement Matters

For cedar to have any effect, the aromatic concentration needs to build up in a confined space. Open closets and large storage rooms dilute the vapour too quickly. Cedar is most effective inside:

  • Sealed cedar chests with reasonably tight lids
  • Zippered garment bags (adding cedar blocks or sachets inside)
  • Small drawers with adequate cedar coverage relative to volume
  • Vacuum-sealed storage bags alongside cedar sachets

Placing a single cedar block on a shelf in a large walk-in closet will have minimal practical effect. The volume of air is simply too large for the concentration to deter moths.

Juniperus virginiana — Eastern red cedar tree
Juniperus virginiana (Eastern red cedar), the source of cedar oil used in moth-repellent products. Image: Wikimedia Commons (CC)

Lavender as a Secondary Deterrent

Lavender (Lavandula angustifolia) contains linalool and linalyl acetate, compounds that moths find repellent. Dried lavender sachets placed among folded garments have a long tradition of use in European linen storage, and the practice translates directly to Canadian households. Like cedar, lavender does not kill larvae — it discourages egg-laying by adult moths in treated areas.

Lavender sachets remain effective for roughly six to twelve months before the scent fades. Crushing dried flowers gently refreshes the volatile content. Sachets stored in sealed bags between seasons retain their potency significantly longer.

Lavandula angustifolia — common lavender
Lavandula angustifolia, the species most commonly used in lavender sachets for textile storage. Image: Wikimedia Commons (CC)

Other Natural Options

Dried Rosemary and Thyme

Rosemary and thyme contain camphor-like volatiles that moths avoid. Small cloth sachets filled with dried herbs can supplement cedar and lavender in drawer storage. The effect is mild and serves more as a complement than a standalone measure.

Cloves and Cinnamon

Both spices produce strong aromatic compounds. Whole cloves sewn into small muslin bags are occasionally used in chest storage. One limitation is that cinnamon and clove oils can stain light-coloured fabrics if direct contact occurs — cloth sachets should be used rather than loose spices.

Neem

Neem-based repellents have a reasonable record of effectiveness against a variety of insect larvae and are sold in some Canadian garden and natural-health stores. Neem oil's strong smell is a practical drawback for garment storage, and fabric contact should be avoided with whites and light colours.

What Natural Repellents Cannot Replace

Natural repellents work best as deterrents against moths seeking new egg-laying sites. They are not remediation tools. If an active infestation is present — larvae visible on fabric, or moth casings found inside packaging — the affected garment must be removed from the storage area, laundered at high temperature or dry-cleaned, and the storage space thoroughly vacuumed before repellents are introduced.

For confirmed infestations, freezing is an effective non-chemical treatment: placing garments in sealed plastic bags and leaving them in a chest freezer at -18°C or below for at least 72 hours kills larvae and eggs without damaging most fibres. Health Canada does not recommend domestic use of naphthalene mothballs in living spaces due to health concerns, and paradichlorobenzene products carry similar cautions.

Canadian context: Canada's climate creates seasonal storage pressure. Wool coats, sweaters, and blankets stored for four to six months during spring and summer are at the highest risk. Cleaning garments before storage and combining cedar or lavender with airtight containment addresses the majority of moth risk in typical Canadian household conditions.

Summary

Cedar blocks and lavender sachets are useful deterrents when used in enclosed storage spaces with clean garments. Neither kills larvae on contact, and neither replaces thorough cleaning before storage. Combining airtight or zippered containment with natural repellents — and refreshing both regularly — provides a practical approach to protecting natural-fibre garments during seasonal storage.

For further reference: Canadian Food Inspection Agency and Tineola bisselliella on Wikipedia.