Assembly Line

How insect repellent is made

The U.S. Army developed DEET in 1946 for soldiers, and civilians could not buy it until it was registered in 1957.

stations
5
things upstream
48
raw sources
17
steps from the ground
9

The short version

Most insect repellent is a spray or lotion built around one active ingredient made in a chemical plant. DEET, the oldest, is produced from an acid and an amine, then diluted into a base and filled into pump bottles or aerosol cans. Higher concentrations beyond 50 percent do not protect longer.

  1. Synthesize the active

    DEET is a slightly yellow oil made in a chemical plant from a toluic acid and an amine. Other actives such as icaridin are made by their own routes.

  2. Dilute into a base

    The active is blended into a carrier. A later formulation added polymers to slow evaporation, and was registered in 1991.

    Goes in
    Ethanol

  3. Check the batch

    Samples are tested so the active ingredient is at the concentration printed on the label.

  4. Fill the bottles

    The liquid goes into pump sprays, lotion bottles or aerosol cans, with concentrations ranging from under 10 percent to nearly 100 percent.

    Goes in
    Aluminum can

  5. Label and box

    Packages are labeled with the concentration of the active ingredient, which is what sets how long the protection lasts.

End of the lineInsect repellent

Worth repeating

  • It was first tested as an agricultural insecticide before its military use began in 1946.
  • The American Academy of Pediatrics considers products at 10 to 30 percent DEET safe on children.
  • About 120 products containing DEET are registered with the EPA, from about 30 companies.

Back to the ground

Follow every input upstream and insect repellent starts as these 17 raw sources.

CornSugarcaneWaterNatural gasCrude oilCoalSugar beetBauxiteSoybeansRapeseedClayAirTitanium oreIron oreSulfurRock saltLimestone

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Sources

These sources say little about the factory steps themselves, so parts of this line are a general description. Treat the details with care, and tell us if you know better.

Cite this page: "How insect repellent is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/insect-repellent

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