In Latin America we would, if smokers, smoke cigars to keep mosquitoes away. I forget who told us but we leached out tobacco and put the water on our exposed skin and it kept the bugs away.
So basically there were some still alive even after the soak. Mealybugs are my nemesis. I'm always looking for new ways to treat them. They love hoyas and once you get them, they are nearly impossible to eradicate.