First, BORACARE goes on clear and once it soaks into the wood, essentially disappears. The wood will appear "wet" when you treat, just as if you washed it down with plain water, but once dry and the material is absorbed, it will go back to exactly as it once looked. Effectively there will be no trace or record the application was ever done.

Second, if you read our POWDERPOST BEETLE CONTROL ARTICLE, you'll learn the holes you're seeing are exit holes. Pupae that are fully developed will exit infested lumber and in this process, they create the holes you see. So they are only "active" for a brief moment. Once the adult drills through the wood surface and makes the hole, it will fly away and the hole is rarely ever used again. So to answer your question; no doubt the holes you see were at one point active but not anymore.

So what should you do? Here's the easy answer. Monitor the area and see if any new holes appear. If they do, it will mean you have more pupae hatching and drilling out which means you have an active infestation. If you don't find any new holes, it means the holes you see are old and there is little chance new ones will appear. But as you'll learn in the article, it's the young of this beetle that does the damage and since there is no way to tell if you have any young still in the wood currently chewing away, some people will opt to get it treated so they can be done with the issue once and for all. Ultimately the choice is yours and should be made based on the level of comfort you have for the situation. It's kind of like insurance; it's hard to have too much. In this case, going through the work of removing the varnish and treating would no doubt be a major task. But once done, the wood would be protected and you'd no longer have to wait and worry about whether or not there is more damage being absorbed.

Alternatively you could wait it out and see if anything new emerges and if it does, use that as a sign there is activity that needs to be addressed before the wood sustains more damage. In the end it's your call and there is no "right or wrong" choice.

Here are direct links to the information and products listed above:

Boracare:  http://www.bugspraycart.com/insecticide/liquid/boracare-gal

Powderpost Beetle Control Article:  http://www.powderpostbeetles.com/powderpost-beetle-control

Should the inside logs be treated as well? There is nothing on the inside logs.

If you read through our POWDERPOST BEETLE CONTROL ARTICLE, you'll learn about several treatment options that can help to deal with a powderpost beetle problem. One important point made in our article is that the typical "borax" application being done will only help to "prevent" future infestations and should not be used where an active problem exists. This is because (as our article explains) the beetle larvae are deep within the logs doing their damage and to kill them you'll need something that will penetrate the wood. Borax cannot penetrate.

And  though products like TIMBOR (very similar to Borax) are fine when you want to stop mold or wood destroying insects from targeting your structure, they should only be thought of as "preventive" and not "curative".  For curing problems, you must use something like BORACARE.  The unique design of the Boracare enables it to both penetrate and kill whatever is living deep within the wood and this is critical if you wish to stop the damage that's clearly happening.

You'll also learn from our article that the holes you're seeing are actually "exit" holes being created as adults hatch from their pupae casings and want to leave the deep and safe confines of the log. In other words, don't get them confused with something that's "entering" the log; quite the opposite is happening. On top this, once these adults emerge, they'll attempt to mate and continue the process so in your case, any logs or other wood you wish to protect must be treated with Boracare ASAP. This treatment will both get the ones currently feeding on the logs as well as prevent future problems from ever starting.

So to answer your question; you most definitely need to have the inside logs treated. Furthermore, the material used must be something like Boracare. Lastly, before you next paint the outside of the cottage, I suggest you treat that side of the cottage as well to insure you get complete and thorough coverage with no weak points available.

Here are direct links to the information and products listed above:

Powderpost Beetle Control:  http://www.powderpostbeetles.com/powderpost-beetle-control

Boracare:   http://www.bugspray.com/catalog/products/page52.html

What you're seeing is not unusual. As our POWDERPOST BEETLE ARTICLE explains, an active infestation can  remain in a small area for a long time. In fact I've seen this happen where the activity is noted in the same area for 10-20 years so it can happen. And your fears are legit; it's entirely possible there is other activity you cannot see. But I wouldn't panic just yet.

Based on your message, it's unclear if you even have beetles. I've seen situations where there has been sawdust falling out of both floor joists and subflooring but it's not been due to insects. Are you actually finding adults and/or exit holes?

Second, it's unclear where exactly where you think this infestation is even located. If you read your words, you say the "active infestation is between the joist" which makes no sense. Generally, the construction one would expect to see looking up while standing on the floor of an unfinished basement would be floor joists with subflooring on top of the floor joists. That means the beetles will have to be in either the floor joists or the subflooring but not "between" them.

Lastly, the fact that you have an unfinished basement could be a big plus in case it turns out you do indeed have a problem. Since all your floor joists should be exposed, they'll be easy to treat. I suggest you start there. If you have carpeting or some other flooring above which can be pulled up to gain access to the subflooring, I suggest you lift this covering and treat both areas with BORACARE. This would surely take care of any insects that might be active in either location. In the process you should be able to better assess any damage already caused so that repairs could be initiated if warranted.

Here are direct links to the information and products listed above:

Powderpost Beetle Article:  http://www.powderpostbeetles.com/powderpost-beetle-control

Boracare:  http://www.bugspraycart.com/insecticide/liquid/boracare-gal

There are two options for such a small icon. The first would be to inject it with some Baygon Aerosol through any cracks or seams in the metal cover. If you don't think this is going to reach deep enough into the wood icon, drill some port holes through the bottom and treat it from this side. You should be able to get good penetration and coverage with the aerosol alone. If you still have activity 2-3 months after treating, you'll need to get some of the Jecta Gel and inject this through access holes on the bottom that can be drilled if needed. The bottom line is you must get this wood treated through and through if you want to kill off the feeding larvae as explained in our Powderpost Beetle Control article.

Powderpost beetles can do a lot of damage if given the chance. In most cases, they're not detected till something significant has been discovered so whats happened is fairly common. Also, it's not uncommon for their activity to be limited to one piece of wood. In other words, they could be in just that one piece (and hopefully so). That being said, the first order would be to treat the wood with activity, along with all the other accessible areas, to insure the problem is not more wide spread and that if it is, the damage won't get worse.

Once the area has been treated with something like the Boracare we have listed in our powderpost beetle control article, it would be wise to get a knowledgeable expert to inspect the floor joist to see what needs to be done. In most cases, "sistering" or attaching another joist to the damaged one will do the job. Leaving the old one in place would be fine and probably best; the new one would then take on the weight of the structure and the old one would be left to support what it can.