Also see the two other blogs in this "Lyme & Ticks" series:
Ticks Everywhere! What to Do: Prevention & If You Get Bit
I have met few people as tasty to biting insects as moi.
No repellent is 100% effective, but they can help reduce the risk of exposure.
Essential Oil-Based Repellents: Re-apply natural essential oil-based sprays at least every half hour. Studies show that most of them lose potency within five to 10 minutes! For children, limit essential oil exposure, spray on clothing, or stick to "barrier methods" (below). Oil-based formulas may last longer (and work better for flies) than alcohol-based blends but can be messy to apply. Combo blends also tend to work better and last longer (more studies). Essential oils best shown to repel ticks and mosquitoes include citronella, lemon eucalytpus (citriodora), lavender, and rose geranium, juniper, often showing comparable repellency to DEET. Although it’s typical to only use two to five percent of essential oils in a formula blend, studies show that 20 to 50% dilutions are generally much more effective (see these studies). Case in point: One study found that 10% lavender and geranium was not a good repellent, but 30% completely repelled ticks.
Yarrow: If you just can't handle the potent aromas of essential oils or want something that's even safer for children and pets, consider yarrow extract. Field studies show it's as effective as DEET for mosquitoes and ticks. Basically, make a fresh plant tincture of the fresh leaves and/or flowering stalks in 80- to 100-proof vodka. Learn more about identifying and using yarrow here. Many herbalists also tincture catnip, tansy, and/or other herbs commonly known to work as essential oils to use as a base for their sprays.
Pyrethrum: Naturally derived from the pyrethrum daisy, this insecticidal isolated compound is toxic to insects and ticks. (Pyrethrins are the active chemicals in pyrethrum but pyrethroids and permethrin are synthetic versions which may work but are not natural nor approved for organic gardens.) Is is safer than most synthetic insecticides but still not 100% nontoxic to humans, and it will also kill beneficial insects and is highly toxic to our beloved bees. More details here. For mosquito and tick repellency, spray this liberally on clothing, then let it dry. It will last for a few washes. The USDA military tests of the synthetic permethrin spray found that it provided 100% protection against ticks of all ages while high-proof DEET provided 86-92% protection. See the permethrin safety fact sheet. Most of what you buy commercially is the synthetic version, but natural and organic pyrethrum is available if you search around -- look for the OMRI label. Learn how to make your own natural spray here.
Barrier Methods: Barrier methods to repel ticks and biting insects work great and are totally safe for kids and animals, but they may not be convenient. This includes long pants tucked into socks/boot, long sleeves, hats, hoodies, and zip-up bug tents for hammocks, the ground, bug nets for your head, deer fly patches for your hat, and even as bug net jackets. Being an apparently very tasty human for whom no synthetic nor natural bug spray has ever worked, this is my #1 method for mosquitoes and flies. (They're less specific for ticks than flying insects.) Oh, yes, it looks super sexy! I even have a pop-up bug tent for the dog to hang in when we're at camp reading in our hammocks. All sorts of bug screens are available for babies, strollers, mini tents, etc.
If you ask me which bug spray I personally use, the answer is generally none of them. Besides being averse to strong smells, none of them actually work for me. In the Guatemalan jungle, I was the only person getting eaten alive (and, ironically, I was the only one wearing an insect repellent... and I was wearing DEET given the location)! Peeing in the woods can result in 10 bites on my tush within 30 seconds, which is why my husband has bestowed upon me the trail name "sweet meat." It's enough to make a gal want to stay inside all summer... but I don't! I do spray my natural bug sprays (usually lavender-rose geranium, Quantum Buzz Away Extreme, or yarrow) periodically, mainly for ticks, but barrier methods and regular tick checks are my go-to.