I have a lot of common fears (drowning, et cetera), but one thing that consistently freaks me out is moths. Also butterflies. I know it sounds ridiculous, but...well, bees, hornets, wasps, flies...they are all annoying and worrisome, what with the painful stingers and all, plus horsefly bites are just awful. But they have one thing going for them: Sound. You can hear them coming, you know when they are near, because of the buzzing. They are like bombing planes. Yeah, you might not be able to avoid them, but at least you can try, and failing that, you can prepare yourself.
Moths and butterflies, on the other hand, are generally much larger than bees or flies, and completely FUCKING SILENT. One second, I'm out on the porch reading a book and enjoying a cigarette, and the next moment some huge, fluttering monstrosity is attempting to make icky insect love to my face. It's creepy and oddly terrifying when I'm not expecting it.