We were last in WDW in summer 2016, a time when there was a lot of concern about Zika virus transmission risk in South Florida. There was complementary insect repellent in our room at the Yacht Club, and spray stations upon entering the parks. I’m not sure if they still do this.
Disney must do a very good job with pest management, as I’ve only experienced a few bites at dusk, etc. The one time I was badly bitten was at Mickey’s Not So Scary Party watching the parade, but I was standing right next to a hedge. Not a smart location choice! It could have been mosquitoes or another biting insect.