A weather-sealed lens shouldn’t let any dust, sand, moisture or other elements inside of it. But weather-sealed doesn’t make it sealed against insects, apparently. Roger and Aaron from Lensrentals recently had a Canon 70-200mm f/2.8L IS II lens dismantled to remove a dead fly from it. Now that’s what I call a bug fix!
Other than removing the fly, Roger and Aaron tested the lens out to see how it affects the image. And surprisingly enough, a dead bug inside a 70-200mm lens doesn’t affect the image quality nearly as much as one would have thought.