I have a log home 2 yrs old. The outside of the home has been treated for insects before the stain and topcoat was applied. This year I’ve noticed small piles of sawdust (caused by a boaring insect.) I saw a very small insect mostly black and like a miniature wasp. The hole it went into was smaller than a NO 2 pensil lead. This is nothing like a carpenter bee; not aggressive at all. Every few weeks I notice a few more piles of saw dust and holes. Is this something I should be concerned about?
Yes. You clearly have a wood boring insect problem and though you’re not exactly sure what it is, there are some things to consider when addressing such a problem. First and foremost, you’ll need to learn exactly what it is. Second, you’ll need to employ a defensive plan that will cover all potential pests. As I’ll explain, even though the logs have “been treated”, there are various forms of treatment that can be done and since you didn’t cite exactly what was used, it’s not clear to me just what level of protection you’ve got in place. So to start, let me explain what options are available and hopefully you’ll be able to figure out what you’ve got so you know what to expect as far as protection from pests.
Logs being treated before stain and topcoat is applied will usually involve one of three formulations. The most common used is a surface spray like TIMBOR. This is supposed to help provide a level of protection against wood rot and boring pests. But it’s a remedial control measure at best. The best option is to apply something like BORACARE which will actually penetrate the wood through and through. The next best option is the NBS ADDITIVE which is ideally used in conjunction with Boracare. When NBS is added to stain or topcoat, you’ll get an extra level of repellency that can last a year or more. It will lie on the surface of the logs, above the Boracare and will act by chasing away insects.
Now what can you expect from any of these treatments? This is important because they all will provide different results. The simple topical treatment first mentioned can help hold off and prevent new entry from wood eating pests like boring beetles. But insects that simply “chew” the wood like CARPENTER BEES won’t be stopped. More importantly, this treatment won’t control or stop anything already living in the logs which is what the Boracare can handle. And since many logs are shipped with pests already present, this can be crucial.
Products like Boracare are the best to have applied because they’ll penetrate the wood through and through so anything present and feeding will die. Treatments can last many years (3-5 on average) and will prevent wood rot as well as stop any feeding insect. But like the topical wood protectors, Boracare won’t stop boring Bees. Carpenter Ants are also immune from the treatment since they don’t eat the wood but rather just bore it out. So how do you stop boring pests that aren’t actually eating the wood?
For that you’ll need to apply something like the NBS or CYPERMETHRIN. The NBS is popular because you can add it to your stain or paint and can get long term protection. But if it wears out before you need to restain, you can mix it up with water and spray it over the areas needing insect repellent as well so it’s pretty versatile. The Cypermethrin can only be used as a spray and will work better as an insect repellent compared to the NBS when used this way. Using it every 1-2 months will usually do the trick but again, it can’t be added to stain or paint so it’s a true spray repellent and not an additive like the NBS.
Now onto your current problem. Clearly you have some kind of wood wasp and it would appear that it’s not eating the wood but rather just boring through it. This means you’ll need to take care of it as explained in our WOOD WASP CONTROL article.
Once their nests have been treated, you would then want to employ some NBS or Cypermethrin to prevent more from coming around. Lastly, you’ll want to have the logs treated with Boracare sometime in the future if they’ve not been treated yet with something that penetrates. And of course, adding some NBS to future applications of stain would be smart as this will cut down on the spraying you’ll need to do.
Here are direct links to the information and products listed above:
Carpenter Bees: http://www.carpenterbees.com/carpenter-bee-control
Wood Wasp Control: http://www.bugspray.com/catalog/products/page1601.html