On your patio, plant lemongrass in planters at each edge of the patio. Not only are they pretty and very fragrant, they will ward off mosquitoes.
Of course a few plants may not take care of all of them, but you also don't want to overload your yard with one plant. There are other plants that also help with warding off bugs including lavender and oh my, lavender is a lovely plant to have planted around the patio. Unlike lemongrass that you would plant in planters, I recommend planting it directly in the ground or you'll miss out on the try beauty of a full grown lavender plant. I also found this great website when I was looking for a few photos that I found to be quite informative: http://www.mnn.com/your-home/organic-farming-gardening/stories/12-plants-that-repel-unwanted-insects. So, when considering what to plant around your patio, check out their suggestions.
Additionally, for your personal use, if you want to use a bug repellent on you, try this mixture:
4 drops of Thyme
8 drops of Lemongrass
4 drops of Lavender
4 drops of Peppermint
Blend those oils together and use in a body oil or unscented body lotion to help keep bugs at bay.
If you are industrious, you can make your own natural candles for your patio as well using true essential oils. The DIY network has a wonderful instructional step-by-step process for making your own candles including the ratio of citronella to wax. Check it out: http://www.diynetwork.com/how-to/make-and-decorate/crafts/bug-off-make-your-own-citronella-candles
Don't let bugs spoil your outdoor fun and don't use toxic chemical products when you can do it all more naturally.
Be Well,
--Kim