DEET really is a toxic substance, and if it weren't that our tolerance for mosquitoes is so low, we probably would have banned its use long ago. DEET was developed by the US military in 1946, if that is any indication of the low level of safety concern in the chemical's development. There are certainly more toxic insect repellents out there, and DEET is much less detrimental to birds and other forms of life than many insect-targeting chemicals, but it still is a chemical that can burn through plastics and synthetics. DEET products strongly discourage its use around the eyes and mouth or simple cuts and scrapes, and users are encouraged to wash the product off as soon as it is no longer needed. Ingestion can be fatal and use on children is discouraged. Fortunately, natural alternatives can be just as effective, and the primary advantage in DEET is simply that it is longer lasting. Multiple applications of natural repellents can overcome this advantage entirely.
Coconut Oil and Lavender Oil
Beautyberry, coconut oil and lavender to repel mosquitos...
We have a huge mosquito problem here, and thanks to the invasion of aggressive Asian Tiger mosquitoes here about 10 years ago, we get attacked all day as well as night. I don't want to be slathering on chemicals but protection is a necessity to enjoy any time in the yard. I've read of various concoctions using a variety essential oils, but didn't have any of the listed ones on hand. In desperation I added about 10 drops of lavender essential oil to a small jar filled with VCO. We dip our fingers in the jar and rub the oil on any exposed skin and around the back of the neck to help keep them away from the face. So far it seems to be doing the trick, and of course the VCO is also a nice skin treatment :)
I'm looking to get some beautyberry bushes to plant as I've just read that they are a great repellent - you can crush the leaves and rub them on and it's apparently as effective as DEET. It also is 100% effective against ticks. In the meantime, my lavender/VCO mixture is definitely helping. I've also seen the info in spraying Listerine around the yard and that does seem to help as well.
Citronella has long been a favorite natural insect repellent, particularly mentioned as a mosquito repellent. The question is, does it work? Citronella coils and candles have become a substantial little industry, but their effectiveness has definitely been called into question. Like other natural insect repellents, citronella oil is the essential oil extract of a certain genus of plants in the lemon grass family. Consensus on lemon grass is that it can be effective as a component of a multi-pronged defense against mosquito attacks. Think about combining citronella candles with a lavender and eucalyptus lotion or mix citronella in with several other herbs and essential oils for an effective mosquito repellent spray.
Mosquito control. Whilst I burn incense coils or sticks, a good neighborly trick that SHOULD be practiced internationally is to install Bat Boxes at regular intervals in the area. Bats consume 10,000 to 15000 insects a day (per bat). Do the community a turn!