My dad acquired some used hives from someone on craiglist for free, this plastic piece came with it. I'm assuming it's an in-hive feeder but can't wrap my head around how it works. I know someone here can enlighten me.
Also put a pic my mom found of me and the neighborhood friends 20-something years ago when we found a swarm and called up the local beek. Pretty funny looking at it now.
I have never used one like this, but I think that you just put it on top of your highest box, fill it up with syrup, put an empty box over top, and then apply the cover. The white sections allow syrup to get into the raised "edges" where the bees can access it, and there should be only limited potential for mass calamity since the bees should have the ability to crawl back up the inside of the screens.
But, I've also been told not to use such feeders if you have top entrances, due to excessive robbing potential. Since the syrup is accessible quite close to the upper entrance, there is little space for any guard bees to keep intruders out. If you use the jar-type or through-inner-cover styles, at least any invaders have to go past 1/2 of the hive thickness before they can reach the entrance to the feeding device, and the access size is limited, so guards can keep it defended like nightclub bouncers. With the 360° of access, plus having a path close to the upper entrance, it may invite unwanted guests.