It's important to use them because they provide a passive way to document pollinator populations without the inescapable biases that come with hand collections. People will inevitably collect brightly colored, large, and slow insects with greater frequency than camouflaged, small, and speedy insects.
So we have to use bee bowls in conjunction with hand collections, no matter how disappointing their results may be.
Here's what they look like in the field:
I was expecting a soapy plethora of pollinator soup. Bug soup it ain't.
We turned up a surprising number of flies (few of which were in the major pollinator family, Syrphidae), and waaaaaay more Japanese beetles than we wanted.
Gross. Those guys are stinky after a couple days.
During the same couple of days that the bee bowls were out, we also performed some hand collections. I'm specifically interested in which pollinator species are active at which wildflower species. The wildflowers that make the final cut will attract a diversity of native bees in fairly large numbers. If a wildflower species only attracts one pollinator species (especially if other wildflowers attract that pollinator just as well) or attracts only small numbers of pollinators, it gets the boot when it's time to recommend a final mix.
In order to do this, we're collecting 25 pollinators from each wildflower species at each site when it is in its most dominant blooming period. That's 150 pollinators total from each wildflower species. We'll later ID those insects as far down as we can--probably to genus or species.
There are a couple different methods for catching pollinators.
The classic (and the one that gets you the most crazy looks from golfers), is an insect net.
Weirdly enough, we found that the best method was to simply use a plastic cup. It was sneakier and allowed for a little more precision.
Unfortunately, both methods resulted in bee stings. Those little jerks got both of my thumbs while I was holding them in the net.
Fortunately, I'm not allergic to bee stings. So far.