The summer is over and the autumn prep continues on the bluebird trail.  I don’t just soap the ceilings in early spring to deter wasps; I also soap any new nestboxes fresh out of the workshop and installed in late summer through autumn before winter sets in.  Here is why.  In my location, we can still have warm days in late October into November.   One autumn day few years ago, I found this mud dauber wasp species(see photo below) and some spiders building nests in corners of the nestboxes by the ceiling.   This happened after the nesting season was completed and no more birds were using the nestboxes.  Unoccupied nestboxes can get re-occupied fast by other species.  After all, it’s a “house”.  It has a roof.  Fresh wood is attractive to insects to overwinter (like the mud dauber wasp does) and for spiders’ cottony webs, an easy stick to untreated wood.   My method of soaping comes from my days as a kid remembering how goopy soap bars can get in soap dishes, even with just a little water that collects in the bottom of the dish.   So I create a soap (think paste) mixture using gentle Ivory soap.  I put two small bars of the Ivory brand bars in a plastic Ziploc container (not a Ziploc bag) that has a screw-top which is leakproof and add a little water.  I use a pastry brush to create the perfect thin soap paste to then “paint” on the inside walls and ceilings of nestboxes (I do this in spring for all nestboxes and fall for new nestboxes).   This deters insects from adhering their nests to the wood.   When I soap, I also soap the outside  sections underneath the nestbox floors.  This is particularly helpful in the summer.  I’ve had carpenter bees try to bore holes on the undersides of the nestboxes.  The photos below show my method.    I find this way so much easier and less hassle than taking bar of Ivory soap and attempting to rub it on the ceiling with my hand–it’s awkward.  It does not cover well and it’s difficult to get in those corners by the ceiling.  By the way, I should mention if boxes are soaped in the spring, I need not add another thin soap layer UNLESS it’s problematic and has recurring wasp problems.  I’ve found I can paint a thin layer on or around March 1 (maybe earlier in warmer weather), and most nextboxes are good to go through the full nesting season.  I don’t have to reapply any soap again (such as between each nesting).   The goal is to have as many nestings in a nestbox in a season.  Once wasps, hornets, and bees use a nestbox, the birds will not.  Some incubating females have been known to abandon a nest with a clutch of eggs.   My philosophy is DETER the problems; thus I soap all my nestboxes in the spring–hopefully just one application is needed.

Other for preparing the nestboxes for roosting birds for those cold winter nights,  my tasks for the nestboxes will be completed until next February, anticipating yet another nesting season in Southwest Virginia on the Woolwine House Bluebird Trail — now at 30 monitored and maintained nestboxes with the trail expansion recently completed.  I might increase it to 33!

This is what I found one October day a few years ago before attempting to “winterize” the nestbox. Inside the mud tunnels (look like organ pipes) are the mud dauber wasp species larvae. The larvae overwinter in the mud tunnels (one larva per tunnel) and free themselves from the tunnels in the spring. When I find these, they are easily removed with a metal paint scraper.

Two bars of Ivory and some water and a pastry brush.   That’s it.  This setup goes in a plastic bag and is taken with me on all nestbox visits.  I keep it in the car in case I need to reapply a problematic nextbox.

 …soaping under the eaves, inside the upper sides of the walls, and all of the ceiling. You can see a thin layer of Ivory soap has been “painted” on the one wall (it’s shiny).  NOT TOO THICK!  Once soaped, make sure it is dried before birds enter the box. It does not take long to dry.  I only do this in unoccupied boxes.  The trick is to have a fairly slick surface with a THIN layer of of the soap film that won’t get on the birds’ feathers when they flap their wings inside the nestbox.  It takes a bit of practice.  I also soap the eaves as I’ve seen insects like spiders build webs in there over the Noel hardware cloth guard but under the roof.  Spider webs are easily removed, actually.   I find using a small stick I find nearby on the ground is a good method to remove spider webs and other cottony insect nests–the web material sticks to this natural tool–easy to throw back on the ground right then and there. Wearing gloves, like garden gloves, is a precaution as I may not know what species of insect it is.  It’s how I do things–better to be safe than sorry.  I doubt any mud dauber wasp can build in this nestbox now!

I soap here on the underside of the OUTSIDE section of the nestbox. This is a good deterent of female carpenter bees boring holes or hornets attempting to attach their gray, cylinder-shaped paper nests here.  I do this section usually just in the spring.  Also, this picture is a good example of good drainage of the nestbox–in the corner sections.  The wood I’m soaping here is western red cedar–the roughcut side.  I keep the insides of the nestbox smooth and put the roughcut sides out.


  1. HI Christine,
    I used your soaping trick in my nest boxes but also on our wood gazebo in between and under the railings to deter wasps from building their paper nests. It really cut down on that problem. Thanks.

    PS in a former reply I mentioned a nestbox my husband and I built. It was our best attempt at a two hole mansion. You asked if we had built it. Yes we did build it. I tried to take the design ideas that seemed most beneficial from a few designs. Linda Violettes two-holer keeping the deeper box, thicknesses and tried to keep the same dimensions but we goofed a little and lost a little bit in the actual area just because we we are still learning and the way we put it together. Its dimensions are still roomier & correct depth. I think we lost a half inch in surface area….. we are novices. We did a larger roof for greater overhang all around but slanted roof to shed water. Also made the holes(2) sort of a rounded corner rectangle 1 1/2 h x 1 1/4 wide suggestion from book ” Songbirds in your Garden” John Terres. Read sparrows fatter and less attractive to them. Although I have seen house sparrows able to enter. I would not of done this width if I lived in the area of Mountain bluebird-Western part of country, as I read they are a little wider round than Eastern Bluebird. The actual door is on a side hinge with a little hook to keep closed. Door fits very tight and is thicker but actually due to a correction we had to make due to a cutting error. However it acts somewhat like a guard on the hole, without giving other birds something to cling to. The venting is above the door which faces opposite the prevailing winds. There are 2 very small weep holes in the floor. Made the floor have a very slight slant towards the weep holes to drain if that ever became an issue. But it has not and has been dry. Put horizontal ridges inside the door to aid in leaving the box. Mounted on a metal pole. Bottom of box sits about 5 ft from ground. Made a baffle – snake guard from designs on your site. We have mostly cats & raccons to worry about and thats why I went with 5ft high-for the base of box . Any higher and I couldnt wipe it out easy- or take out sparrow nests which does happen. I do grease the pole. Nothing toxic. Put wood glue over all seams. Used natural pine.
    Things I would do different.
    1. Couldnt find a solid peice of wood for roof in larger size we needed. There was a seam which we used wood glue to reinforce and keep water out and it has worked but will try and replace with a solid peice of wood.
    2.Would do best to keep correct internal dimensions. An error in cutting the door made it narrower than it should of been so it fitted in the opening instead of overlapping it. We added another peice of wood on top of it to overlap the box so it ended up actually giving greater protection from wind and rain but cutting down on the inside dimensions. We could replace this in future. Like I said we are not really skilled at this. Our first attempt.
    3. Would add additional depth to box to allow for screening-blowfly on floor to keep correct deeper box depth as per Linda Violettes box.
    Sorry I took so long to respond to your question. Thank you for all your great information Christine.
    Best wishes. Char


  2. This email seems very interesting, but is difficult to read, due to the words and pics running off the page sideways really badly. Is there another way to view it?




    • Marianne, sorry for the trouble you are having reading the Email. It appears to be a miss-communication with formats from my post. The reason you received the Email is you subscribed to my blog. Just go to my main page of my website/blog and read the post there at the top. There are several different size photos in it, which could have caused an issue on your end. Thanks for writing! If it continues with future posts, please let me know, and I’ll look deeper into eliminating the problem, if possible, on my end.


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