I just want to get a thread on the internet about this plant; Cotinus spp. Mine is a Cotinus coggygria. It took me two days of research to identify this plant, and nowhere does the internet mention bees and other pollinators flocking to it. Well, my tree currently can be heard buzzing from 40 ft. away.
There is also a U.S. native species, Cotinus obovatus. Both species come in many cultivars, and some cultivars may be more attractive to bees than others as some cultivars rarely flower ( I guess ).
Twigs have solid pith: