Don't remember where I read or heard it, but crawling insects will not cross a line of mint plants. Mint also repels black flies and mosquitoes, I can vouch for that. If you have a mint plant just take some of the leaves and rub them where you don't want the insects, for the flying kind just take a few leaves and chew on them, worked great for everyone up in Maine at a friends house in warmer months.
Another great product for ticks and chiggers, is Badger Anti-Bug spray, it's all organic and perfectly safe for kids and adults sprayed right on the clothes and skin. I have used it for a couple of years now and I have not gotten one stinken chigger bit or tick bite. Can't use it for dear though as it does have an odor.