An insect repellent (also commonly called "bug spray") is a substance applied to skin, clothing, or other surfaces to discourage

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s (and

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s in general) from landing or climbing on that surface. Insect repellents help prevent and control the outbreak of insect-borne (and other

-bourne) diseases such as

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. ...

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the '' Borrelia'' bacterium, which is spread by ticks in the genus '' Ixodes''. The most common sign of infection is an expanding red rash, known as erythema ...

dengue fever Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...

bubonic plague Bubonic plague is one of three types of plague caused by the plague bacterium ('' Yersinia pestis''). One to seven days after exposure to the bacteria, flu-like symptoms develop. These symptoms include fever, headaches, and vomiting, as wel ...

, river blindness, and West Nile fever. Pest animals commonly serving as vectors for disease include insects such as

flea Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, ...

fly Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

, and

mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...

; and

tick Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living ...

s (arachnids). Some insect repellents are

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed t ...

s (bug killers), but most simply discourage insects and send them flying or crawling away. Nearly any would be fatal upon reaching the

median lethal dose In toxicology, the median lethal dose, LD50 (abbreviation for " lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is ...

, but classification as an insecticide implies death even at lower doses.

Effectiveness

Synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic ...

repellents tend to be more effective and/or longer lasting than "natural" repellents. For protection against mosquito bites, the U.S. Centers for Disease Control (CDC) recommends

DEET ''N'',''N''-Diethyl-''meta''-toluamide, also called DEET () or diethyltoluamide, is the most common active ingredient in insect repellents. It is a slightly yellow oil intended to be applied to the skin or to clothing and provides protection a ...

picaridin Icaridin, also known as picaridin, is an insect repellent which can be used directly on skin or clothing. It has broad efficacy against various arthropods such as mosquitos, ticks, gnats, flies and fleas, and is almost colorless and odorless. A s ...

(icaridin, KBR 3023), oil of lemon eucalyptus ( para-menthane-diol or PMD),

ethyl butylacetylaminopropionate Ethyl butylacetylaminopropionate (trade name IR3535) is an insect repellent which is applied topically to prevent bites and stings from mosquitos, ticks, and other insects. It is a colorless and almost odorless oil, has efficacy against a broad ran ...

and 2-undecanone with the caveat that higher percentages of the active ingredient provide longer protection. In 2015, Researchers at

New Mexico State University New Mexico State University (NMSU or NM State) is a public land-grant research university based primarily in Las Cruces, New Mexico. Founded in 1888, it is the oldest public institution of higher education in New Mexico and one of the state's ...

tested 10 commercially available products for their effectiveness at repelling mosquitoes. On the mosquito ''Aedes aegypti'', the vector of Zika virus, only one repellent that did not contain DEET had a strong effect for the duration of the 240 minutes test: a

lemon eucalyptus ''Corymbia citriodora'', commonly known as lemon-scented gum and other common names, is a species of tall tree that is endemic to north-eastern Australia. It has smooth white to pink bark, narrow lance-shaped to curved adult leaves, flower buds ...

oil repellent. All DEET-containing mosquito repellents were active. In one comparative study from 2004, ethyl butylacetylaminopropionate was as effective or better than

in protection against ''Aedes aegypti'' and ''Culex quinquefasciatus'' mosquitoes. Other sources (official publications of the associations of German physicians as well as of German druggists) suggest the contrary and state DEET is still the most efficient substance available and the substance of choice for stays in malaria regions, while ethyl butylacetylaminopropionate has little effect. However, some plant-based repellents may provide effective relief as well.

Essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

repellents can be short-lived in their effectiveness. A test of various insect repellents by an independent consumer organization found that repellents containing DEET or picaridin are more effective than repellents with "natural" active ingredients. All the synthetics gave almost 100% repellency for the first 2 hours, where the natural repellent products were most effective for the first 30 to 60 minutes, and required reapplication to be effective over several hours. Although highly toxic to cats, permethrin is recommended as protection against mosquitoes for clothing, gear, or bed nets. In an earlier report, the CDC found oil of lemon eucalyptus to be more effective than other plant-based treatments, with a similar effectiveness to low concentrations of DEET. However, a 2006 published study found in both cage and field studies that a product containing 40% oil of lemon eucalyptus was just as effective as products containing high concentrations of DEET. Research has also found that neem oil is mosquito repellent for up to 12 hours. Citronella oil's mosquito repellency has also been verified by research, including effectiveness in repelling ''

Aedes aegypti ''Aedes aegypti'', the yellow fever mosquito, is a mosquito that can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito can be recognized by black and white markings on its l ...

'', but requires reapplication after 30 to 60 minutes. There are also products available based on sound production, particularly

ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...

(inaudibly high-frequency sounds) which purport to be insect repellents. However, these electronic devices have been shown to be ineffective based on studies done by the United States Environmental Protection Agency and many universities.

Safety issues

For humans

Children may be at greater risk for adverse reactions to repellents, in part, because their exposure may be greater. Children can be at greater risk of accidental eye contact or ingestion. As with chemical exposures in general, pregnant women should take care to avoid exposures to repellents when practical, as the

fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...

may be vulnerable. Some experts also recommend against applying chemicals such as DEET and sunscreen simultaneously since that would increase DEET penetration. Canadian researcher, Xiaochen Gu, a professor at the University of Manitoba’s faculty of Pharmacy who led a study about mosquitos, advises that DEET should be applied 30 or more minutes later. Gu also recommends insect repellent sprays instead of lotions which are rubbed into the skin "forcing molecules into the skin". Regardless of which repellent product used, it is recommended to read the label before use and carefully follow directions. Usage instructions for repellents vary from country to country. Some insect repellents are not recommended for use on younger children. In the DEET Reregistration Eligibility Decision (RED) the

United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...

(EPA) reported 14 to 46 cases of potential DEET associated

seizures An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with lo ...

, including 4 deaths. The EPA states: "... it does appear that some cases are likely related to DEET

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...

," but observed that with 30% of the US population using DEET, the likely seizure rate is only about one per 100 million users. The Pesticide Information Project of Cooperative Extension Offices of

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...

states that, " Everglades National Park employees having extensive DEET exposure were more likely to have insomnia, mood disturbances and impaired cognitive function than were lesser exposed co-workers".Deet
/ref> The EPA states that citronella oil shows little or no

and has been used as a topical insect repellent for 60 years. However, the EPA also states that citronella may irritate skin and cause

dermatitis Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved c ...

in certain individuals. Canadian regulatory authorities concern with citronella based repellents is primarily based on data-gaps in

toxicology Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating e ...

, not on incidents. Within countries of the European Union, implementation of Regulation 98/8/EC, commonly referred to as the Biocidal Products Directive, has severely limited the number and type of insect repellents available to European consumers. Only a small number of active ingredients have been supported by manufacturers in submitting dossiers to the EU Authorities. In general, only formulations containing DEET, icaridin (sold under the trade name Saltidin and formerly known as Bayrepel or KBR3023), ethyl butylacetylaminopropionate (IR3535) and citriodiol ( p-menthane-3,8-diol) are available. Most "natural" insect repellents such as citronella, neem oil, and herbal extracts are no longer permitted for sale as insect repellents in the EU due to their lack of effectiveness; this does not preclude them from being sold for other purposes, as long as the label does not indicate they are a

biocide A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. The US Environmental Protection Agency (EPA) uses a sli ...

(insect repellent).

Toxicity for other animals

A 2018 study found that Icaridin, is highly toxic to

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. T ...

, in what the authors described as conservative exposure doses. The LC50 standard was additionally found to be completely inadequate in the context of finding this result.

Permethrin Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto clothing or mosquito nets to kill the insects th ...

is highly toxic to cats but not to dogs or humans.

Common insect repellents

Common synthetic insect repellents

Benzaldehyde Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor. ...

, for bees * Butopyronoxyl (trade name Indalone). Widely used in a "6-2-2" mixture (60% Dimethyl phthalate, 20% Indalone, 20% Ethylhexanediol) during the 1940s and 1950s before the commercial introduction of DEET *

(''N'',''N''-diethyl-''m''-toluamide) *

Dimethyl carbate Dimethyl carbate is an insect repellent. It can be prepared by the Diels–Alder reaction of dimethyl maleate and cyclopentadiene Cyclopentadiene is an organic compound with the formula C5H6.LeRoy H. Scharpen and Victor W. Laurie (1965): "St ...

* Dimethyl phthalate, not as common as it once was but still occasionally an active ingredient in commercial insect repellents *

Ethyl butylacetylaminopropionate Ethyl butylacetylaminopropionate (trade name IR3535) is an insect repellent which is applied topically to prevent bites and stings from mosquitos, ticks, and other insects. It is a colorless and almost odorless oil, has efficacy against a broad ran ...

(IR3535 or 3- 'N''-Butyl-''N''-acetylaminopropionic acid, ethyl ester) * Ethylhexanediol, also known as Rutgers 612 or "6-12 repellent," discontinued in the US in 1991 due to evidence of causing developmental defects in animals * Icaridin, also known as picaridin, Bayrepel, and KBR 3023 *

Methyl anthranilate Methyl anthranilate, also known as MA, methyl 2-aminobenzoate, or carbomethoxyaniline, is an ester of anthranilic acid. Its chemical formula is C8H9NO2. It has a strong and fruity grape smell, and one of its key uses is as a flavoring agent. Che ...

and other anthranilate-based insect repellents *

Metofluthrin Metofluthrin is a pyrethroid used as an insect repellent. The vapors of metofluthrin are highly effective and capable of repelling up to 97% of mosquitoes in field tests. Metofluthrin is used in a variety of consumer products, called emanator ...

is a contact

rather than a repellent * SS220 is a repellent being researched that has shown promise to provide significantly better protection than DEET * Tricyclodecenyl allyl ether, a compound often found in synthetic perfumes

Common natural insect repellents

Oil Jar in cow horn for mosquito-repelling pitch oil , a by-product of the distillation of wood tar

Beautyberry ''Callicarpa'' (beautyberry) is a genus of shrubs and small trees in the family Lamiaceae.Heywood, V.H., Brummitt, R.K., Culham, A. & Seberg, O. 2007: Flowering Plant Families of the World. Royal Botanic Gardens, Kew. They are native to eas ...

(Callicarpa) leaves *

Birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' cont ...

tree bark is traditionally made into

tar Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. "a dark brown or black bi ...

. Combined with another oil (e.g., fish oil) at 1/2 dilution, it is then applied to the skin for repelling mosquitos * Bog Myrtle (Myrica Gale) *

Catnip ''Nepeta cataria'', commonly known as catnip, catswort, catwort, and catmint, is a species of the genus '' Nepeta'' in the family Lamiaceae, native to southern and eastern Europe, the Middle East, Central Asia, and parts of China. It is widely ...

oil whose active compound is Nepetalactone * Citronella oil (citronella candles are not effective) *

of the

(''Corymbia citriodora'') and its active compound p-menthane-3,8-diol (PMD) *

Lemongrass ''Cymbopogon'', also known as lemongrass, barbed wire grass, silky heads, Cochin grass, Malabar grass, oily heads, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family. Some ...

Neem oil Neem oil, also known as margosa oil, is a vegetable oil pressed from the fruits and seeds of the neem (''Azadirachta indica''), a tree which is indigenous to the Indian subcontinent and has been introduced to many other areas in the tropics. It ...

* Tea tree oil from the leaves of '' Melaleuca alternifolia'' *

Tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

Insect repellents from natural sources

Several natural ingredients are certified by the

as insect repellents, namely

catnip ''Nepeta cataria'', commonly known as catnip, catswort, catwort, and catmint, is a species of the genus '' Nepeta'' in the family Lamiaceae, native to southern and eastern Europe, the Middle East, Central Asia, and parts of China. It is widely ...

oil, oil of

(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 acts 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 Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed t ...

while others are only repellent. Below is a list of some natural products with repellent activity: * '' Achillea alpina'' (mosquitos) * alpha- terpinene (mosquitos) * ''

Andrographis paniculata ''Andrographis paniculata'', commonly known as creat or green chiretta, is an annual herbaceous plant in the family Acanthaceae, native to India and Sri Lanka. It is widely cultivated in Southern and Southeastern Asia, where it has been believe ...

'' extracts (mosquito) * Basil ** Sweet basil ('' Ocimum basilicum'') *

Breadfruit Breadfruit (''Artocarpus altilis'') is a species of flowering tree in the mulberry and jackfruit family ( Moraceae) believed to be a domesticated descendant of '' Artocarpus camansi'' originating in New Guinea, the Maluku Islands, and the Phil ...

(Insect repellent, including mosquitoes) * '' Callicarpa americana'' (

beautyberry ''Callicarpa'' (beautyberry) is a genus of shrubs and small trees in the family Lamiaceae.Heywood, V.H., Brummitt, R.K., Culham, A. & Seberg, O. 2007: Flowering Plant Families of the World. Royal Botanic Gardens, Kew. They are native to eas ...

) *

Camphor Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel (''Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the k ...

(mosquitoes) *

Carvacrol Carvacrol, or cymophenol, C6H3(CH3)(OH)C3H7, is a monoterpenoid phenol. It has a characteristic pungent, warm odor of oregano. Natural occurrence Carvacrol is present in the essential oil of ''Origanum vulgare'' (oregano), oil of thyme, oil obt ...

(mosquitos) *

Castor oil Castor oil is a vegetable oil pressed from castor beans. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its density is 0.961 g/cm3. It includes a mixture of triglycerides in which about ...

(''Ricinus communis'') (mosquitos) *

oil (''Nepeta'' species) ( nepetalactone against mosquitos) * Cedar oil (mosquitos, moths) * An example of ineffective herbal insect repellent

Celery Celery (''Apium graveolens'') is a marshland plant in the family Apiaceae that has been cultivated as a vegetable since antiquity. Celery has a long fibrous stalk tapering into leaves. Depending on location and cultivar, either its stalks, ...

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 Cinnamon is a spice obtained from the inner bark of several tree species from the genus '' Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakf ...

( leaf oil kills mosquito larvae) * Citronella oil (repels mosquitos) (contains insect repelling substances, such as citronellol and

geraniol Geraniol is a monoterpenoid and an alcohol. It is the primary component of citronella oil and is a primary component of rose oil, palmarosa oil. It is a colorless oil, although commercial samples can appear yellow. It has low solubility in w ...

) *

Clove oil Oil of clove, also known as clove oil, is an essential oil extracted from the clove plant, '' Syzygium aromaticum''. Clove oil is commonly used in aromatherapy and for flavoring food and some medicines. Madagascar and Indonesia are the main produc ...

(mosquitos) * D-

Limonene Limonene is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the oil of citrus fruit peels. The -isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring a ...

(ticks, fleas, flies, mosquitoes, and other insects) (widely used in insect repellents for pets) *

Eucalyptus oil Eucalyptus oil is the generic name for distilled oil from the leaf of ''Eucalyptus'', a genus of the plant family Myrtaceae native to Australia and cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmaceutical, anti ...

(70%+ eucalyptol), (cineol is a synonym), mosquitos, flies,

dust mites House dust mites (HDM, or simply dust mites) are various species of acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing allergies. Biology Species The curren ...

In the U.S., eucalyptus oil was first registered in 1948 as an insecticide and miticide. *

Fennel Fennel (''Foeniculum vulgare'') is a flowering plant species in the carrot family. It is a hardy, perennial herb with yellow flowers and feathery leaves. It is indigenous to the shores of the Mediterranean but has become widely naturalized ...

oil (''Foeniculum vulgare'') (mosquitos) *

Garlic Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northeas ...

(''Allium sativum'') (Mosquito, rice weevil, wheat flour beetle) * Geranium oil (also known as ''

Pelargonium graveolens ''Pelargonium graveolens'' is a ''Pelargonium'' species native to the Cape Provinces and the Northern Provinces of South Africa, Zimbabwe and Mozambique. Etymology ''Pelargonium'' comes from the Greek πελαργός ''pelargos'' which means st ...

'') * 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) *

oil (''Cymbopogon'' species) (mosquitos) ** East-Indian lemon grass (''

Cymbopogon flexuosus ''Cymbopogon flexuosus'', also called Cochin grass, East-Indian lemon grass or Malabar grass, is a perennial grass native to India, Sri Lanka, Burma, and Thailand. It is placed in the genus ''Cymbopogon'' (lemongrasses). Its essential oil is pr ...

'') *

Linalool Linalool () refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of ...

(ticks, fleas, mites, mosquitoes, spiders, cockroach) * Marigolds (''Tagetes'' species) *

Marjoram Marjoram (; ''Origanum majorana'') is a cold-sensitive perennial herb or undershrub with sweet pine and citrus flavours. In some Middle Eastern countries, marjoram is synonymous with oregano, and there the names sweet marjoram and knotted marj ...

(spider mites '' Tetranychus urticae'' and '' Eutetranychus orientalis'') *

Mint MiNT is Now TOS (MiNT) is a free software alternative operating system kernel for the Atari ST system and its successors. It is a multi-tasking alternative to TOS and MagiC. Together with the free system components fVDI device drivers, XaAE ...

(

menthol Menthol is an organic compound, more specifically a monoterpenoid, made synthetically or obtained from the oils of corn mint, peppermint, or other mints. It is a waxy, clear or white crystalline substance, which is solid at room temperature ...

is active chemical.) ( Mentha sp.) *

(''Azadirachta indica'') (Repels or kills mosquitos, their larvae and a plethora of other insects including those in agriculture) *

Nootkatone Nootkatone is a natural organic compound, a sesquiterpenoid, and a ketone that is the most important and expensive aromatic of grapefruit, and which also occurs in other organisms. Previously, nootkatone was thought to be one of the main chemical ...

(ticks, mosquitoes and other insects) *

Oleic acid Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish. In chemical terms, oleic acid is classified as a monounsaturated o ...

, repels

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfami ...

s and ants by simulating the "

smell of death Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish. In chemical terms, oleic acid is classified as a monounsaturated omega ...

" produced by their decomposing corpses. * Pennyroyal (''Mentha pulegium'') (mosquitos, fleas,) but very toxic to pets *

Peppermint Peppermint (''Mentha'' × ''piperita'') is a hybrid species of mint, a cross between watermint and spearmint. Indigenous to Europe and the Middle East, the plant is now widely spread and cultivated in many regions of the world.Euro+Med Plantb ...

(''Mentha'' x ''piperita'') (mosquitos) * Pyrethrum (from ''Chrysanthemum'' species, particularly ''C. cinerariifolium'' and ''C. coccineum'') *

Rosemary ''Salvia rosmarinus'' (), commonly known as rosemary, is a shrub with fragrant, evergreen, needle-like leaves and white, pink, purple, or blue flowers, native plant, native to the Mediterranean Region, Mediterranean region. Until 2017, it was kn ...

(''Rosmarinus officinalis'') (mosquitos) * Spanish Flag (''

Lantana camara ''Lantana camara'' (common lantana) is a species of flowering plant within the verbena family ( Verbenaceae), native to the American tropics. It is a very adaptable species, which can inhabit a wide variety of ecosystems; once it has been introdu ...

'') (against Tea Mosquito Bug, '' Helopeltis theivora'') * Tea tree oil from the leaves of '' Melaleuca alternifolia'' *

Thyme Thyme () is the herb (dried aerial parts) of some members of the genus ''Thymus'' of aromatic perennial evergreen herbs in the mint family Lamiaceae. Thymes are relatives of the oregano genus '' Origanum'', with both plants being mostly indigen ...

(''Thymus'' species) (mosquitos) * Yellow nightshade (''

Solanum villosum ''Solanum villosum'', the hairy nightshade, red nightshade or woolly nightshade, is a sprawling annual weed in Europe, western Asia, northern Africa, North America, and is also naturalized in Australia. Description An annual herb, to 70 ...

''), berry juice (against '' Stegomyia aegypti'' mosquitos)

Less effective methods

Some old studies suggested that the ingestion of large doses of

thiamine Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thi ...

(vitamin B₁) could be effective as an

oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid ** Oral administration of medicines ** Oral examination (also known as an oral exam or or ...

insect repellent against mosquito bites. However, there is now conclusive evidence that thiamin has no efficacy against mosquito bites. Some claim that plants such as wormwood or sagewort, lemon balm, lemon grass, lemon thyme, and the mosquito plant (Pelargonium) will act against mosquitoes. However, scientists have determined that these plants are "effective" for a limited time only when the leaves are crushed and applied directly to the skin. There are several, widespread, unproven theories about mosquito control, such as the assertion that vitamin B, in particular B₁ (

garlic Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northeas ...

, ultrasonic devices or

incense Incense is aromatic biotic material that releases fragrant smoke when burnt. The term is used for either the material or the aroma. Incense is used for aesthetic reasons, religious worship, aromatherapy, meditation, and ceremony. It may also b ...

can be used to repel or control mosquitoes. Moreover, manufacturers of "mosquito repelling" ultrasonic devices have been found to be fraudulent,Lentek International-08/28/02
/ref> and their devices were deemed "useless" according to a review of scientific studies.

Alternatives to repellent

People can reduce the number of mosquito bites they receive (to a greater or lesser degree) by: * Using a

mosquito net A mosquito net is a type of meshed curtain that is circumferentially draped over a bed or a sleeping area, to offer the sleeper barrier protection against bites and stings from mosquitos, flies, and other pest insects, and thus against the ...

* Wearing long clothing that covers the skin and is tucked in to seal up holesNatural & Alternative Mosquito Repellents
/ref> * Avoiding the outdoors during

dawn Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's ...

and dusk, when mosquitos are most active * Keeping air moving to prevent mosquitos from landing, such as by using a fan * Wearing light-colored clothing (light objects are harder for mosquitos to detect)Micro Wave: Why Mosquitoes Bite You More Than Your Friends
/ref> * Reducing exercise, which reduces output of

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

used by mosquitos for detection

History

Testing and scientific certainty were desired at the end of the 1940s. To that end products meant to be used by humans were tested with model animals to speed trials. Eddy & McGregor 1949 and Wiesmann & Lotmar 1949 used

mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

, Wasicky et al 1949 canaries and

guinea pig The guinea pig or domestic guinea pig (''Cavia porcellus''), also known as the cavy or domestic cavy (), is a species of rodent belonging to the genus '' Cavia'' in the family Caviidae. Breeders tend to use the word ''cavy'' to describe the ...

s, Kasman et al 1953 also

s, Starnes & Granett 1953

rabbit Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit sp ...

s, and many used

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Adult females are referred to as cows and adult ...

References

External links

2011 review of studies of plant-based mosquito repellents - NIH

* * * * ttp://www.ars-grin.gov/cgi-bin/duke/chemact.pl?INSECT-REPELLENT+BORNEOL Plant parts with Insect-repellent Activity from the chemical Borneol (Dr. Duke's Phytochemical and Ethnobotanical Databases)]
Mosquito repellents; Florida U

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