The fall lovebugs don't really get to WDW until late October, so you shouldn't be too worried about it, Laura.
They're completely harmless, just annoying. When they land on you, you have to physically touch them for them to fly off, otherwise they're just nice and content sitting on your leg.
They are EVERYWHERE, though. If you look at the ground, you'll see a million little black dots (aka, squashed bugs).
I've been in late September/early October twice, and I've learned to just get used to them.