In my surroundings a couple of people / friends have the feeling that the number of insects has declined over a number of years.
Do you know of any sources of data which give quantitative numbers on insects per area over time for any country in Western Europe, Americas, Australia, where insect can be:
- bees (wild type)
- or any similar indicator species?
A time range over more than 20 year would be appreciated. If the data set also included confounding factors, this would be a plus.
It seems that biodiversity measures a slightly different number, and for example I wasn't able to find interesting data sets on the European Environmental Agency's website for biodiversity (besides decline in common birds in Europe).
Any hints or tips where to look or what to search for?