We have some mean gnats in the late spring and early summer in the Midwest. I have used Vanilla extract it works ok. I have used Citronella oil works great but strong smelling and burns the skin a little. I use Bug Soothers a bug repellant made locally. It works ok and smells good. I recently have been using Dettol. It is an antiseptic soap. It works great and last for a long time. I mix mine half Dettol and half water in a small bottle that makes a fine mist. Just spray a bit on and it works and lasts. It has pine oil in it and reminds me of pine sol. Here is a link to where I bought mine.
<!-- m --><a class=\"postlink\" href=\"http://www.ebay.com/itm/Dettol-Liquid-First-Aid-Antiseptic-750-ML-25-35oz-USA-SELLER-FAST-SHIP-/191339914797?pt=LH_DefaultDomain_0&hash=item2c8cbf662d\" onclick=\"window.open(this.href);return false;\">http://www.ebay.com/itm/Dettol-Liquid-F ... 2c8cbf662d</a><!-- m -->
<!-- m --><a class=\"postlink\" href=\"http://www.ebay.com/itm/Dettol-Liquid-First-Aid-Antiseptic-750-ML-25-35oz-USA-SELLER-FAST-SHIP-/191339914797?pt=LH_DefaultDomain_0&hash=item2c8cbf662d\" onclick=\"window.open(this.href);return false;\">http://www.ebay.com/itm/Dettol-Liquid-F ... 2c8cbf662d</a><!-- m -->