Simple solution:
Permathrin
And permathrin is not a repellant. It is an insecticide. i.e. it KILLS them.
Check this out:
http://www.tickinfo.com/permethrin.htm
We have a lot of insects in central KY. I discovered permathrin and just spray it on all my outdoor work clothing. It lasts for many washings. And it is really hard for human skin to absorb it.
So be sure to add that warning.
Pyrethrin is naturally occurring in daisies and chrysanthemums. I’ve been reading up on natural plants that are insect repellent due to my mother developing an interest. You’d be surprised. Plant basil in between your tomatoes, they don’t just taste good together.