Several natural ingredients are certified by the United States Environmental Protection Agency as insect repellents, namely catnip oil, oil of lemon eucalyptus (OLE) (and its active ingredient p-Menthane-3,8-diol), oil of citronella, and 2-Undecanone, which is usually produced synthetically but has also been isolated from many plant sources.
Many other studies have also investigated the potential of natural compounds from plants as insect repellents. Moreover, there are many preparations from naturally occurring sources that have been used as a repellent to certain insects. Some of these act as insecticides while others are only repellent. Below is a list of some natural products with repellent activity:
* Achillea alpina (mosquitos)
* alpha-terpinene (mosquitos)
* Andrographis paniculata extracts (mosquito)
* Basil
** Sweet basil (Ocimum basilicum)
* Breadfruit (Insect repellent, including mosquitoes)
* Callicarpa americana (beautyberry)
* Camphor (mosquitoes)
* Carvacrol (mosquitos)
* Castor oil (Ricinus communis) (mosquitos)
* Catnip oil (Nepeta species) (nepetalactone against mosquitos)
* Cedar oil (mosquitos, moths)
*  Celery extract (Apium graveolens) (mosquitos) In clinical testing an extract of celery was demonstrated to be at least equally effective to 25% DEET, although the commercial availability of such an extract is not known.
* Cinnamon (leaf oil kills mosquito larvae)
* Citronella oil (repels mosquitos) (contains insect repelling substances, such as citronellol and geraniol)
* Clove oil (mosquitos)
* D-Limonene (ticks, fleas, flies, mosquitoes, and other insects) (widely used in insect repellents for pets)
* Eucalyptus oil (70%+ eucalyptol), (cineol is a synonym), mosquitos, flies, dust mites In the U.S., eucalyptus oil was first registered in 1948 as an insecticide and miticide.
* Fennel oil (Foeniculum vulgare) (mosquitos)
* Garlic (Allium sativum) (Mosquito, rice weevil, wheat flour beetle)
* Geranium oil (also known as Pelargonium graveolens)
* Hinokitiol (ticks, mosquitos, larvae)
* Lavender (ineffective alone, but measurable effect in certain repellent mixtures)
* Lemon eucalyptus (Corymbia citriodora) essential oil and its active ingredient p-menthane-3,8-diol (PMD)
* Lemongrass oil (Cymbopogon species) (mosquitos)
** East-Indian lemon grass (Cymbopogon flexuosus)
* Linalool (ticks, fleas, mites, mosquitoes, spiders, cockroach)
* Marjoram (spider mites Tetranychus urticae and Eutetranychus orientalis)
* Mint (menthol is active chemical.) (Mentha sp.)
* Neem oil (Azadirachta indica) (Repels or kills mosquitos, their larvae and a plethora of other insects including those in agriculture)
* Nootkatone (ticks, mosquitoes and other insects)
* Oleic acid, repels bees and ants by simulating the "smell of death" produced by their decomposing corpses.
* Pennyroyal (Mentha pulegium) (mosquitos, fleas,) but very toxic to pets
* Peppermint (Mentha x piperita) (mosquitos)
* Pyrethrum (from Chrysanthemum species, particularly C. cinerariifolium and C. coccineum)
* Rosemary (Rosmarinus officinalis) (mosquitos)
* Spanish Flag (Lantana camara) (against Tea Mosquito Bug, Helopeltis theivora)
* Tea tree oil from the leaves of Melaleuca alternifolia
* Thyme (Thymus species) (mosquitos)
* Yellow nightshade (Solanum villosum), berry juice (against Stegomyia aegypti mosquitos)