Every fall our house fills with ladybugs. Until now, we painstakingly removed them one by one with a water glass/paper, if we were lucky enough to catch them.
I cannot find the source where I read about it, but apparently ladybugs are usually looking for water to drink. As an experiment, we soaked some paper towel and held it up near the ladybugs and they latched on and wouldn’t let go! I could walk around the house collecting them, and all the ones that were already on the wet paper wouldn’t fly away. Even after I put them outside, they would stay on the paper towel until it dried out.
This made collecting them very easy. We would bring out dozens at a time on the same piece of paper towel.