Synopsis

Source of validity: Traditional
Rating (out of 5): 2

Thuja plicata (Western Red Cedar) has a longstanding history of traditional use by Indigenous peoples of the Pacific Northwest, particularly as an insect repellent. Ethnobotanical records indicate that various parts of the tree, especially its leaves and bark, were used to deter mosquitoes and other insects. The methods included burning the foliage to produce a smoke that repelled insects, or placing branches in dwellings and other areas to keep bugs away. The aromatic compounds found in the foliage—primarily thujone and other volatile oils—are believed to contribute to this effect, as their strong scent can be unpleasant or even toxic to many insect species.

However, scientific research directly evaluating the efficacy of Thuja plicata as an insect repellent is limited. While some studies on related species (such as Thuja occidentalis) and their essential oils suggest potential insect-repelling properties, robust clinical or laboratory data for Thuja plicata itself are sparse. The available evidence for its use as an insect repellent is, therefore, based mostly on traditional practices and anecdotal reports rather than rigorous scientific validation. As a result, the evidence level is rated as 2, reflecting its significant traditional use but limited modern scientific support.

More about Thuja plicata
More about Insect Repellant

Other ingredients used for Insect Repellant

Other health conditions supported by Thuja plicata

Products containing Thuja plicata