once in awhile a queen gets lost and under a sbb, but usually at this time of year, yellow jackets are trying to get in through any possible spot, including the screen, and those are guard bees down there.
I pull my sticky boards during the summer, my bees sit in full sun on 100 degree days, shade after 3 or 4 pm, so they need the ventilation. I am about to oil the boards and put them back tomorrow when I also do my split and maybe go get my trap out bees (I don't know, I kinda favor leaving them over where it rained and all that golden rod is..)