Could you just slide the old nest out from under the new one? Then you could check it for parasites, and also it makes the new nest lower so other birds can't reach in and grab the young. I'm pretty sure the old, flattened nest should be easy to separate from the new one.

Wow, this sure has been the year for third clutches. This should help increase the Bluebird population. Congrats on your third nesting!

Karen no problem. You put it on after first egg. Any box would do. In fact it's a big joke about the cheese-its but I love them and since it worked so well the first time about 4 or 5 years ago I won't use anything else! LOL What happened is I had blues and eggs in a box way in the back of my yard (first nest of the year) and all of a sudden I heard that dreaded sound. I had planned to make one out of wood with sides on it but hadn't got around to it yet. They came the earliest I'd ever seen that year and my husband is a carpenter so of course we always have wood around but hardly ever have any tools around here. I had to leave that day and so I had to come up with something quick. All I had was duct tape and that was my biggest box. I have had the same one last 2 nestings with no problem but I put a lot of tape on the inside of all the corners and those front corners too. I just screw it to the sides of the top of the box like you would with the mono fishing line for hosps and maybe tape the top and sides down to the box or you can tack it on with finish nails driven part way in and just bend them over or use thumbtacks. Make sure you have at least 2 1/2" of clearance so they can get in. I completely cover the hole so mine come down pretty far but I haven't had any casualties since I started using these. Karen just make sure they can figure it out. Sometime young birds will have a problem with this BUT eventually they always find their way in. The couple this year was not very bright. I had to take it off the second morning so she could lay her next egg and I put it right back on when she was done. She got it the third day. My Tres have been vigilant enough to not need one but one lady on Bet's site has used a guard with Tres successfully. I just think it kind of goes against their grain. You know the way they look out of the hole for each other and change places so fast. You know what I'd do with those wrens? I'd take a piece of cardboard and tack it to the front of the box covering the hole and run some duct tape down the outside corners so it looks like the guard from the front. I do this with empty boxes in my yard to try to teach them when they see this it means no entry just in case you have a persistent bird it may help next year. Hope it helps Cathy

We have one at both houses. I'm not positive which generation and I'm not at either place to check. I think they're both 3rd. It took me a long time to feel comfortable with them. Our HVAC contractors included them as part of our new HVAC system but barely gave instructions. Google bought Nest years ago but never fully integrated it into their home division. Customer service was spotty but has improved in the last two years and online support has been good too. I really like the capability of checking and changing temperature settings from my phone. If we decide to drive up to PA I can raise or lower the temp from my phone and then when we arrive it's the temp we want. When the furnace died in PA a few years ago I could see that the system was calling for heat but the inside temperature was still lower than the setting. If it had dropped to 55 the Low Temperature Alert on our Alarm System would have notified us. But we were able to call our contractor and he repaired it before the temp dropped that low. Maire