With all this talk of Robber screens lately I've been considering making some of my own. I have some hardware cloth in some junk somewhere and was wondering if the bees would propolize it if the screen is small. Should I just go out and buy some #8 hardware cloth instead?
They won't propolize it because it is outside the colony, or at least not to any extent that will hinder it. I would suggest only using them on weak hives that need them. See Tillie's recent post. You could hinder them more with the robber screen than by letting them defend themselves. If you really do have a robbing problem start by reducing the entrance to a size they can defend as a first step.
The bees won't propolize them at all. I use a couple of nails in predrilled holes so they are easy to add and remove.
As far as disrupting hive activities, after a couple of days, they don't even pay attention to them.
Last year I left them on through the winter to see if it affected bees activities. The good news was it didn't. The bad news is that without a 3/8 x 3/8 opening near the hive entrance, virgin queens couldn't get back in. I need to change the picture and drawings on http://nordykebeefarm.com/forum/forum_topics.asp?FID=6 to reflect this. In past years, I would put them on in July and remove them in October, so it wasn't a problem I was aware of. I even incorperated a robber screen in my KTBH!
Thanks for the reply Robo. I don't intend to use the robber screens right away, I had never really looked into them before and I have had a couple of instances of robbing where they would have come in real handy. I intend to make some just to have on hand when needed. I do have a couple of weak hives, one fron a split and one from a new feral colony I removed from the side of a house. I have their entrances reduced right now but since I don't see the hives that often would it be a good idea to slip the robbing screens on one night and leave them until the hives build up a little more?
Thanks for your reply to Jon. I'm a little confused about the virgin queens not being able to get back in. Do the robbing screens act as queen includers and not allow the queens to leave and enter the hive as well? Is an unmated virgin queen small enough to get out before mating but then too big to return after mating?
Using Robber Screens is a preventive measure. It's like getting an oil change. It's too late when the symptoms appear. It gives me peace of mind that I don’t have to worry about robbing when I am away and can’t do anything about it.
The other thing they are good for is moving. With a strip of wood across the top, and now a little plug in the opening, you can move hives and they have good ventilation, too.
Virgin queens go out just like the other bees, but every hive I had robber screens on went queenless after swaming.
Doing a little research, I found that queen breeders that used robber screens on their mating nucs recommended adding a 3/8 x 3/8 opening near the hive entrance for the virgin to get back in.
I don't know why they are exceptions.
Thanks for clearing that up Jon, I'll be sure to look at your plans and include that opening. I already had one hive go queenless and don't want another. :D
Here's a link to the plans in case you can't find them:
http://nordykebeefarm.com/forum/forum_posts.asp?TID=24&PN=2