Bees and wasps in our garden disappeared suddenly last year - I asked a question about it at Why our bees might have suddenly disappeared. This year, I see that some bumblebees are active now. I'd like to measure the population of bees and wasps in the garden over the year, and see if the numbers change when the nearby fields are sprayed.
I note the question How best to count bees entering and leaving a hive to measure hive activity? but I don't have a hive to count. Our bees come from far away, and I'm interested in multiple species from multiple nests, and wasps too. So I'd need to count the number visiting the garden. But, can I count reliably? It will vary with weather, and the number on any one plant will vary greatly depending on plant flowering dates.
Is there any established protocol for counting bees and wasps in the wild to look for population changes over time?
I can't spend too much time on this - I might manage an hour every week. Or, I could set up camera recording, if someone knows some really clever software to do the counting. But I still can't imagine how to overcome the variation.