The name for the troubling observation that where windscreens used to be covered in squashed bugs after a long drive, these days you’ll tend to see your windscreen remains squashed-bug free.
It’s believed this reflects a real and significant decline in insect numbers. Though tracking insect numbers is, however, rather tricky as you could imagine. So don’t ignore bugs, or treat them as pests, value them and, if you have a garden, try to provide some habitat to help them out. Here’s a good article about the windscreen phenomenon.