When I was growing up in the 80's I remember we used to have lots of wild honeybees visiting flowers in our yard. By the 90's the number had dropped precipitously.
I can count the honeybees I have seen over several years(5-6) in our yard on one hand.
This is one of those little things that people didn't notice...until it was very obvious. My guess is that that amount of poisons people use on flower gardens and lawns....basically took most of the bee population. I've seen people put way too much out...and it has to have some kinda effect.