Hello Karen,
First a warning: The essential oils that are used on dogs to repel ticks and
fleas can be toxic to the animals. Additionally, I find that if an insect is interested
enough it will ignore all sorts of essential oils and synthetic chemicals. On humans essential oils can be put on clothing and kept off our body, so using it continuously is not as hazardous as on a dog where it is put on its hair and ends up on the animals skin and may even be licked off by them. So, I am careful how much I put on. People seem to be more aware of the neurotoxicity of many of the essential oils than they use to be. Years back, there were many people overdosing their animals and causing symptoms and even killing them from essential oils. I don't hear about this much any more. There is dog clothing you can get and put the essential oils on there. I am going to copy part of an article I wrote on the meat allergy caused by Ticks below, as I list essential oils show to repel the Lone Star Tick. If you want to read the whole article about this tick induced meat allergy it is pretty interesting. It appears chiggers are also associated with this meat allergy. :
https://youarethehealer.org/ticks-and-chiggers-causing-severe-alpha-gal-meat-allergy/
Prevention
I usually use essential oils to repel insects. I found a great research article that evaluated DEET and eight essential oils for their ability to repel the lone star tick. It turned out that Oregano essential oil was the most effective, followed by Clove, Thyme, Vetiver, Sandalwood, Cinnamon, Cedarwood and Peppermint oils. None of them however were as effective as DEET. "The effective concentration of DEET that repels 50 % of ticks (EC50) was estimated at 0.02 mg/cm2, while EC50s of the essential oils fell between 0.113 and 0.297 mg/cm2. "
One of the issues with essential oils is that they are volatile. That means they will volatilize into the air and disappear. This means you have to reapply the oils often. The warmer it is, the more often they have to be applied. They
should be applied to clothing rather than the skin, as the essential oils can become neurotoxins, or have other toxicities when applied in large amounts to the skin. I usually make up a spray with a base of 25-30% by volume of alcohol, using 95% strength alcohol(such as everclear) and 70-75% by volume of water. The essential oil can be added to this alcohol/water mix. The alcohol is necessary to keep the essential oil in solution. You still have to shake it before applying as the alcohol/water base and essential oil will disassociate over time while sitting.
A research study released this week showed excellent repellency of Tagetes patula (common french marigold), used as a tincture to repel the tick Rhipicephalus microplus, a tick that causes huge loss of livestock.
For an article on everything you want to know about ticks, and how they transmit disease, as well as what to do if bitten, check out this tick article at the Tisserand Institute. It additionally has a recipe for use of essential oils in various types of bases.
https://tisserandinstitute.org/tick-talk-2/