Mosquitos carry some nasty diseases. Bring repellent with DEET. You can find it in wipes if you don't want to send a bottle or spray can.
I've been bitten many times by mosquitos while at WDW and it's no fun to itch your way through a holiday.
Also, there are tiny stinging gnats called "no see ums" that will make your life miserable. You'll not feel them stinging, but you will certainly feel the itching a bit later.
The Health Department still has a warning issued regarding mosquitos, which recommends in part, using spray with DEET, staying indoors in the early am and at dusk, and keeping the body covered with light colored clothing.
Don't use perfume or hairspray either. Scented powders and scented deodorant are other items to avoid.