If they are trying to attach a paper nest to the underside of your deck, spraying WD-40 on the spot will keep them from building there. But there are also German yellow jackets that nest in holes in the ground....or in a crack in your siding and get into your walls. That's nasty stuff! If they are going into a hole in your house, call an exterminator....my son landed in the ER because he was attacked when he accidentally disturbed a nest! Nasty bugs!! Linda C PS my son is a grown man, past 40...not a child!

I don't have a lot of experience with the monofilament line. You should register at bluebird nut cafe and post there as well, it is a little more active than this forum. I visit both sites daily. http://bluebirdnutcafe.yuku.com/forums/63/The-Bluebird-Chatter-Forum-Our-Main-Discussion-Area/The-Bluebird-Chatter-Forum-Our-Main-Discussion-Area

Anita, I have a similar situation in that my bluebirds are back for a second brood. The house wrens didn't bother the box during nest building (and the box had been empty for about a month and there were no sticks). Mama laid her 1st egg this morning and this evening, a house wren took out that egg and smashed it at the base of the box. I think that now I'd say "the rule is that there are NO RULES!" I've had house wrens attack several eggs or several chicks, never just one egg. As far as putting up a wren guard, the problem you have is that the house wren has been in the box. And where there is one house wren, there are usually more near by. The reasoning behind the general rule of putting the wren guard on the box when the 1st egg is laid is that the female is less likely to abandon the nest if she can't figure out the wren guard. It's also hard to say whether your female is 'with egg' and I'd hate to see her not be able to get into the box to lay her 1st egg, if that makes any sense. You could wait till it's afternoon and the bluebird hasn't laid an egg and put it on. If she can't figure it out, I'd take it off till the afternoon of the next day, etc. Good luck, Linda in NW GA...

They both help build the nest. I was only able to see them both in the nest box briefly. They were not spending the night in it though. Recently they started putting down in the middle and for the first time there is a chickadee sleeping in it for the night so I'm thinking it is the female and it's close to laying some eggs. I was hoping to get a better focus on the camera Saturday night but was surprised to see the chickadee in the box sleeping. I'm wondering if I should risk opening the box and adjusting the camera quickly tomorrow?