The American Mosquito Control Association press release for Mosquito Control Awareness week recommends that you defend yourself:
Properly apply an approved repellent such as DEET, picaridin, IR3535 or oil of lemon-eucalyptus
This advice reflects the recommendations of the Center for Disease Control; These products are registered with Environmental Protection Agency (EPA). Click here to find out more about their efficacy.
Oil of lemon eucalyptus is a plant-based product. Read the mosquito repellant label, just as you would read a food label, to find out about what is inside.
You may find other “herbal”, plant-based products that work for you for sale. Plus, the web is full of make-it-at-home recipes, some of which may be of dubious value. Research, though, conducted by the U.S. Department of Agriculture has found catnip (Nepeta cataria) and beautyberry (Callicarpa americana) to be effective.
Mechanical means also work, like the jacket modeled above by Wil Jones on 3-4-2013 on a chilly day field trip to the Maritime Hammock Sanctuary. For warmer days, light-colored, loose-fitting clothes through which She cannot poke her proboscis may be helpful.