StirlingCollies
 (Collie Breeders in Minnesota)
 

 
Some of the more common oils that act as flea and insect repellents are: lavender, citronella, cedar, peppermint, eucalyptus and lemongrass.

Lavender
A sweet-smelling, all-purpose insect repellent, lavender essential oil performed well in recent studies as both a tick deterrent and a method of preventing tick eggs from hatching. Additionally, Ohio State University recommends it for controlling fleas. A 2007 South African study found that formulas containing diluted lavender at rates of 10 to 20 percent lavender performed well as tick repellents when compared artificial DEET (N,N-diethyl-m-toluamide) sprays.

Citronella
Oil of citronella naturally repels insects such as mosquitoes, black flies, fleas and ticks, therefore, preventing bites. Citronella oil is a natural, non-toxic alternative to chemical insect repellents such as DEET , therefore, is usually the preferred choice. A combination of the citronella oil and cedarwood oil also helps to repel mosquitoes.

Cedar
A wonderfully fragrant oil that provides a pheromone interruption agent that impairs the insects mental capacity and repels them.  I use cedar shavings around their kennel areas.

Peppermint
An oil high in menthol - it repels fleas, spiders and even mice.

Eucalyptus
While better known for its anti bacterial properties it is a great natural pest deterrent as well.

Lemongrass
Deters fleas and especially ticks. According to Ohio State University. Lemongrass oil contains a pleasing citrus scent that is useful in controlling oily scalps and skin conditions, making it suitable for use on dogs with skin conditions in lotion, spray, soap and shampoo formulas.

Please use ONLY therapeutic grade essential oils . I only recommend and personally use Young Living Essential oils and products as they are pure and safe enough to be taken internally - I don't know of any other essential oils that are as pure.

Essential oil formulations will need to be applied more frequently than synthetic pesticides, but the benefits far outweigh the exposure to harsh chemical smells and toxic side effects. They are great for misting your dog's legs (and your own) any time that you go out where ticks/mosquito/fleas would likely be found.

Basic instructions for a tick, mosquito or flea spray for dogs:
Up to 10 drops or so of any of the insect repelling oils or combination of the same in a 32 oz spray bottle. Shake well and mist your dog daily. This may also be sprayed on bedding or around doorways and baseboards in your home to keep insects out.