In-Depth Guide to DEET as an Insect Repellent

DEET Chemical Composition

DEET, or N, N-diethyl-meta-toluamide, is a chemical compound that falls under the category of insect repellents. Its chemical structure consists of three main components: diethyl, toluene, and amide. The "diethyl" part refers to two ethyl (C2H5) groups, "toluene" represents a methylbenzene ring (C7H8), and "amide" indicates the presence of a carbonyl group attached to a nitrogen atom. The complete formula for DEET is C12H17NO.

This chemical composition is designed to interfere with the sensory mechanisms of insects, making them less likely to land on or bite individuals who have applied DEET.

DEET Development History

DEET was developed by the U.S. Army in 1946 for use by military personnel operating in areas with large populations of mosquitoes and other biting insects. Following further development and testing, DEET was registered for use by the general public in the United States in 1957. It has since become one of the world's most widely used insect-repellent active ingredients and has been extensively studied for its effectiveness against mosquitoes, ticks and other biting insects.

Today, DEET is available in a wide range of insect-repellent formulations and concentrations, with different products designed for different environments, activities and durations of protection.

How DEET Works to Repel Insects

DEET is highly effective at discouraging mosquitoes and other biting insects from landing on and biting treated skin. Although DEET has been used for decades, exactly how it produces this repellent effect is complex and continues to be studied.

Research indicates that DEET interacts with the sensory systems insects use to detect and assess potential hosts. Rather than simply making people “invisible” to mosquitoes, DEET appears to interfere with the chemical cues and receptors insects use when deciding whether to approach, land and feed.

Interfering With Insect Senses

Mosquitoes use a combination of cues to locate potential hosts, including carbon dioxide, body odours, heat and other chemical signals. DEET affects the insects' chemosensory system — the receptors involved in detecting smells and tastes — helping to discourage them from landing on treated skin.

Repellent Effect on Treated Skin

When DEET is applied correctly, it forms a repellent layer on exposed skin. Mosquitoes and other susceptible biting insects approaching the treated area are less likely to land and feed.

The duration of protection depends on factors including the DEET concentration, individual product formulation, environmental conditions and activity. Always follow the application and reapplication instructions supplied with the product.

Broad-Spectrum Protection

DEET can provide protection against a range of biting insects and arthropods, including mosquitoes, ticks and biting flies. This broad effectiveness is one reason it remains widely used for outdoor activities and travel, particularly where biting insects can transmit disease.

While DEET insect repellents are highly effective, it is important to follow the manufacturer's instructions for application, reapplication and concentration. Always check the individual product instructions before applying DEET to clothing or equipment, as DEET can damage some plastics, synthetic materials and other surfaces.

When applied to exposed skin, use DEET only as directed on the product label and avoid the eyes, mouth, cuts and irritated skin. If you have concerns about using a particular product, check its instructions or seek appropriate medical or travel-health advice.

Still unsure about DEET? Read our Debunking DEET Myths: Separating Fact From Fiction guide for answers to common questions and misconceptions about DEET.