The Science Behind Red Cedar: How It Repels Moths Naturally

Discover the science behind cedar woods ability to scramble moth senses and deter larvae without any toxic chemicals with natural compounds like cedrol.

February 8, 2024
min read
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For generations, cedar wood has been valued for its ability to naturally repel moths without the need for hazardous chemicals. But what is it exactly about cedar that moths seem to detest? This article will take a deep dive into the scientific reasons behind red cedar’s incredible power to banish moths and other insects in a safe, non-toxic way.

An Introduction to Red Cedar

Red cedar, with the scientific name Juniperus virginiana, refers to a species of juniper tree native across Eastern North America. It belongs to the cypress plant family. The aromatic, reddish-hued heartwood of red cedar is naturally resistant to insect damage and decay.

Red cedar is commonly harvested to produce furniture, fencing, decking, and other durable outdoor products. But the wood also has a long history of being used as a natural insect and moth deterrent. Red cedar trunks would line closets or chests to protect clothes from hungry moth larvae. Cedar chips are still used today as pet bedding to repel fleas.

But what makes red cedar so effective compared to other woods? The secret lies in some special natural compounds within the wood itself.

Key Active Ingredients in Red Cedar

There are several unique organic compounds found abundantly in red cedar heartwood that provide its insect-repelling powers. The most important are:


Cedrol is the name given to a group of similar organic alcohol compounds present in cedarwood oil. It makes up about 15% of the essential oil. Cedrol has a fresh, woody, balsam-like aroma that we find pleasant. But most insects have receptors that detect it as a warning signal.

Several studies have confirmed cedrol’s ability to effectively repel and even kill moths and larvae. Concentrations as low as 4% are toxic to clothes moth larvae. The vapours disrupt moth pheromones and ovipositioning. Even mosquitoes, roaches, and ants avoid cedrol.


Thujopsene is an organic hydrocarbon and one of the main components of cedarwood oil. Research indicates that thujopsene can deter mosquito biting by up to 96% when tested in vapor form against certain species.

Like cedrol, thujopsene confuses insect olfactory senses through their antennae receptors. It masks the scents they follow to locate mates, food sources and places to lay eggs. The strong woody odour overwhelms their ability to detect pheromones.


Cadinene is a tricyclic sesquiterpene that occurs naturally in cedarwood. Studies focusing on a type of cadinene called gamma cadinene showed significant larvicidal activity against clothes moths. Cadinene was able to kill moth larvae while also repelling adult moths.

These three compounds, along with other minor terpenes, give red cedarwood its potent moth-repelling properties when released as vapors into the air. But how exactly do these vapours deter moths?

How Cedar Repels Moths: Behavioural & Physiological Effects

When we place cedar objects in confined spaces like boxes and trunks, the compounds slowly turn from solid form into airborne vapor. These vapours can repel and disrupt moths through several mechanisms:

Camouflaging Pheromone Signals

Male moths locate female moths for breeding by detecting their pheromone trails with highly sensitive receptors. The strong aroma of cedar helps mask these pheromone chemical signals, preventing males from finding and attracting females.

Deterrent Odors

Moth antennae have receptors specifically tuned to detect and avoid danger signals like predatory scents or toxic chemicals. To moths, the predominant woody notes of cedar indicate a threatening environment to be avoided.

Confusion & Repellency

The complexity of cedarwood aroma can confuse moth senses, overriding their ability to detect suitable breeding and egg laying sites nearby. The vapor is powerfully repellent, causing moths to vacate areas where cedar scent is present.

Larvicidal Effects

Certain compounds like cedrol are directly toxic to moth larvae and eggs. Even in low concentrations, cedar fumes can kill larvae and inhibit eggs from hatching in treated areas.

Anti-Feedant Properties

Some of the terpenes and phenols in cedar can suppress the moth larvae's appetite, discouraging them from feeding on materials where cedar odour is present. Starvation eventually leads to death.

So in summary, red cedar deters moths through a combination of behaviour modification, sensory disruption, toxicity, and feeding deterrence. This multi-modal action makes cedar an extremely effective repellent. But what makes red cedar superior to other wood types when it comes to moth prevention?

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Why Red Cedar Beats Other Woods for Moth Protection

There are a few key reasons why red cedar is unmatched by other types of wood when it comes to repelling moths naturally:

Higher Essential Oil Content

Compared to pine, fir, and other conifers, red cedar contains a significantly greater amount of essential oils per weight - up to 10X more oil than other woods. This means it takes far less red cedar to produce moth-repelling vapors. More bang for your buck.

Greater Proportion of Effective Compounds

Oil derived from red cedar wood contains a uniquely high percentage of moth-fighting chemicals like cedrol and cadinene compared to other wood oils. More of the active ingredients insects detest.

More Durable, Longer Lasting Wood

Red cedar heartwood is naturally resistant to decay thanks to the protective oils. It erodes slowly, providing long-lasting vapor emission compared to pine or other softwoods. You'll get years of service from quality cedar objects.

Synergistic Effects of Multiple Compounds

The complexity of red cedar oil, with many complementary terpenes and phenols, creates an aroma profile that is powerfully confusing and repulsive to moth senses.

So red cedar has the ideal combination of abundant oils, high levels of key insecticidal compounds, and durable wood to provide long-term moth deterrence not found in other woods.

Now that we’ve covered the active chemicals in red cedar and how they deter moths, let's examine some scientific studies proving red cedar's effectiveness.

Scientific Research Validating Cedar's Moth-Repelling Abilities

There is firm scientific evidence to back up red cedar's ability to naturally repel moth infestations. Here are some key studies confirming its efficacy:

Efficacy Against Clothes Moths

A 2017 study tested red cedar oil and chips against common clothes moths. Just a 1% concentration of cedar oil killed larvae and inhibited egg hatching. Cedar chips reduced adult moth lifespan by 50%.

Repellency Against Pantry Pests

Research in 2008 evaluated cedar materials against various Indian meal moth life stages in stored grain. Cedar repelled adults, lowered egg laying by 80%, and reduced larval survival by nearly 99%.

Protection of Wool Items

Scientists in 1962 tested red cedar chests against wool fabric damage. Chests with 1/2" cedar lining resulted in 100% fabric protection from clothes moth larvae.

Impact on Mosquito Biting Rates

In field trials, exposure to cedar oil reduced mosquito biting rates by up to 82% compared to controls. The effects lasted for several hours.

Toxicity to Flea Larvae

Studies reveal that cedar oil can achieve nearly 100% mortality in flea larvae. It disrupts cell membranes in the larvae within 24 hours of exposure.

The evidence clearly indicates that red cedar is powerfully effective at protecting items from moth damage and repelling other insects through completely natural means.


In conclusion, red cedar is an ecologically sustainable, renewable way to reap potent moth and insect protection without any toxic chemicals. The wood’s unique composition - dense essential oils and high levels of compounds like cedrol and thujopsene - provide multi-faceted moth deterrence when slowly released as vapor.

Red cedar confuses moth senses, hides pheromone trails, creates a repellent environment, and can directly kill larvae. There are few wood types as durable, long-lasting, and effective as red cedar for natural insect prevention. Extensive scientific research has validated its ability to safely keep moths at bay.

Rather than spraying hazardous pesticides in your home or releasing toxic chemical fumes, rely on the time-tested power of red cedar. Its comforting, fresh aroma will send invading moths packing while keeping your family and possessions safe from harm.

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Our mission is to empower you with the knowledge to curate a wardrobe that not only reflects your personal style but also aligns with environmentally friendly practices. From exploring the wonders of natural mothballs and sustainable garment storage to diving deep into DIY solutions and green living, we're here to guide you on a journey towards a more eco-conscious, stylish, and intentional lifestyle.

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