Natures mosquito repellents are effective at repelling mosquitoes and preventing bites as well as curtailing the spread of diseases which mosquitoes carry. No mosquito repellant is 100% effective, either natural or synthetic ones. Different types of mosquitoes react to varying stimuli in different ways. Most mosquitoes are active at dawn or dusk, some hunt your blood during daylight. The mosquito that bites you as you sip your morning coffee is not the same little bugger that sucks your blood by moon light.
Gardeners may also wish to plant mosquito-repelling plants in their yards and gardens and attain favorable results. These results will never be as good as concentrated essentail oils but they are helpful in keeping mosquitoes at bay.
DEET based products are the most popular commercial product used to keep mosquitoes off of you. DEET however has a multitude of issues and side effects, not the least of which is brain damage . Hey - I mean whats a little brain damage so long as get rid of those nasty mosquitoes - right ?
Plants that are considered repellents synthesize one or more of several natural compounds. Pyrethrins, methyl-nonyl-ketone, geraniol, estragole, citronellal, limonene and nerolidol.
There are a gazillion varieties of basil, it's a fragrant herbaceous plant that is grown by multiple cultures. One purported property of Basil is its ability to repel flies. Growing some basil indoors some say will keep those annoying house flies away. See: Basil Repels Flies
Field studies in Africa found that potted basil provided roughly 40% protection against malaria carrying mosquitoes. Other studies using the essential oils topically showed nearly 100% protection for around 6 hours against yellow fever mosquitoes.
Most Plants that are considered mosquito repellents synthesize one or more of several natural compounds. Pyrethrins, methyl-nonyl-ketone, geraniol, estragole, citronellal, nerolidol and limonene . As it turns out Basil has 4 of these volatile compounds.
Catnip also known as catmint is in the Mint family and has many of the same attributes as other types of Mint. In the gardening realm it is frequently grown in "tea-gardens" or paired up with up other plants for its qualities as a companion plant. Catnip - the plant - repels some harmful insects , flea beetles in particular but also has some effectiveness on mosquitoes.
The essentail oils form catnip serves as a natural mosquito repellant when applied topically, and your cat, as well as any nearby ferile felines will love you for it.
Citronella is one of the best known mosquito repellants. It is not 100% effective, nothing is. but studies have proven its effectiveness. Ounce for ounce citronella OIL is as effective as Deet .
The citronella plant itself is another subject alltogether. It is claimed that the plant will repel mosquitoes within a roughly 10-foot radius due to its aromatic oils. Although research has verified claims regarding concentrated citronella oil it has repeatedly failed to back up claims regarding the plant itself 'au naturelle'.
Another confusing element of the citronella saga is the fact that there are several distinct species of plants that answer to the name 'citronella' . Citronella grass is the most popular among home gardeners. It is effective at warding off some insects such as whiteflies. It is also the plant used for to make citronella oil commercially, the oil found in citronella candles, soaps and so forth. Citronella grass by itsef however is only mildly repulsive to mosquitoes, only in its synthesized concentrated form can it measure up to commercial products.
Topical applications of 100% citronella essential oil can provide complete protection against multiple types of mosquito for up to 2 hours in a laboratory setting.
The very same cloves you use in baking and pickling is effective at repelling mosquitoes.
In 2013 Clove essential oil was coupled with other essential oils as carrier oils, and tested for mosquito repellent properties. A 2004 study reported that Pure, undiluted clove essential oil worked against several mosquito species for 2 to 4 hours.
Eugenol is a component found in cloves and synthesized for use in many commercial products for use against multiple insects.
Lavender not only smells good, it serves as a natural insect repellent. It's eco-friendly and not harmful to people or pets. A Lavender spray mist will keep gnats and mosquitoes at bay. Lavender planted in strategic locations will also help to keep them away when trying to enjoy your yard, patio, garden or pool. Lavender itself does not actually repel the mosquito per se, but simply blocks out their ability to smell out food sources. They have a limited olfactory system and lavender oil blocks the ability of the mosquito to smell out food sources - namely you.
The plant itself is mildly repulsive to somes mosquitoes, the essential oils are more effective.
Lemon eucalyptus essential oil contains some of the same compounds as citronella in fact its essential oil is over 80% citronellal. Oil from the leaves of the Lemon eucalyptus tree is applied to the skin as an insect repellent. It is used for preventing mosquito as well as tick bites.
One study proved that a formula containing 32% lemon eucalyptus oil provided roughly 95% protection against mosquitoes for 3 hours. Lemon eucalyptus essential oil has been demonstrated to work effectively in comparison to DEET. 
Lemon Grass essential oil is a natural mosquito repellent. A 2015 study demonstrated that lemongrass essential oil coupled with olive oil as a carrier provided nearly 100% protection against SOME mosquito varieties.
Topical applications are believed to provide 75% or better depending on multiple variables.
Lemongrass is also proven effective against mites and ticks as well .
Researchers tested Neem Oil against DEET mosquito repellent. A solution of 20% neem oil provided 70% protection for 3 hours between dusk and dawn. DEET provided a similar level of protection, but it lasted for about 8 hours. Well Deet wins out in this case, but neem doesn't cause brain damage.
Peppermint is another natural mosquito repellant in high concentrations. Peppermint essential oil has been proven effective against mosquito larvae and bites from several varieties of mosquitoes for over 2 hours. At the University of Delhi in India it was proven to be effective in repelling mosquitoes, but not extremely so.
As a mosquito repellant, Thyme is on your side, but personally I never seem to have enough thyme. Thyme can be an effective mosquito repellent for short durations. A study at Iowa State University's Department of Entomology led by Donald R. Lewis found that lemon thyme (Thymus X citriodorus) is more effective than citronella and roughly 62 percent as effective at repelling mosquitoes in comparison to DEET.
Burning thyme leaves can repel mosquitoes for up to 90 minutes. Topical applications of thyme essential oil can provide 90 to 97% protection against common mosquitoes for almost 1.5 hours.
Warnings and Caveats
Some essential oils make the skin more susceptible to sun damage.
Some people are sensitive to some esentail oils particularly hwen applied topically. It is advisable to test any oils on a small patch of skin first.
Essential oils should not be used on irritated skin or near open wounds.
1. Essential oil analysis and field evaluation of the citrosa plant "Pelargonium citrosum" as a repellent against populations of Aedes mosquitoes.
2. Stress and Combined Exposure to Low Doses of Pyridostigmine Bromide, DEET, and Permethrin Produce Neurochemical and Neuropathological Alterations in Cerebral Cortex, Hippocampus, and Cerebellum
2A. DEET Mosquito Repellents Linked to Brain Damage
3. Field evaluation of three plant-based insect repellents against malaria vectors in Vaca Diez Province, the Bolivian Amazon.
4. Sigma-Aldrich Plant Profiler