If it's a rove beetle blister (which it may very likely be, as regular insect bites don't cause blisters), the only way to try to keep them away are:
a) After sunset, keep all lights off or cover the windows. They're attracted by bright lights and can easily sneak anywhere.
b) Avoid leaving sources of humidity outside. Their more common habitat are rice fields and other areas with shallow water. If you have plant vases with water collecting at the bottom, or clothes dropping water on the ground/releasing humidy etc etc, they'll think that your window/balcony/roof is a nice hotel.
In theory they're harmless and actually useful, as they hunt annoying insects. Unfortunately they produce some nasty acid. I only got a very light blister while cycling, a flying one bumped into me. My wife got a few nasty blisters, though. Our situation at home has improved a lot after we started to make sure that in the afternoon there are no lights on unless the typhoon-windows are sealed. We have the kind of cover that looks like many layers of metal, the Chinese name is "thousand leaves window". They block all the light and last year we've not had a single rove beetle at home, even though we live surrounded by rice fields and there are plenty of them crawling around the first floor.
As a side note: they're REALLY tough to kill. Their body is armored. If you find one at home, don't use a tissue to kill it, and even rubber shoes may not get the job done. I usually try to grab something larger than my palm, possibly made of wood or hard plastic (well, at least two years ago...last year luckily we've not had any visit). If you find one of your body it's hard not to panic, but the ideal solution is to try to blow it away.