Any new home that shows signs of this pest should at least provoke some concern by the homeowner. Based on your message, I would say more than just "concern" is warranted. In fact, I would say a clear course of action is required and here's what I recommend.

First, remove the Ashwood flooring. Next, treat the subflooring with BORACARE. After allowing it to dry (1-2 days) lay the oak flooring and then treat it with Boracare. After this cures you can proceed with whatever type of stain or finish you prefer and you'll be beetle free. This is the only way to know for sure you've got protection in place no matter if they are in the subflooring or the new wood being installed.

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

Hardwood Floor Treatments:  http://www.powderpostbeetles.com/powderpost-beetle-control#wood_floor_beetle_treatment

Thanks,
X.

First, it is not possible to judge if you have high quality or low quality wood based on whether insects are present or not. Most all wood is susceptible to insects; hardwood flooring is particularly vulnerable and though oak is strong, it's rare that any home installation of wood floors won't show some insect activity old or new. So if you like the look and the company is reputable, I'm sure they used a good grad of wood as it's hard to mask or get away with using anything less when it comes to good quality wood flooring.

As for the holes you see; you didn't mention if the activity appears to be new or old. This is important. As mentioned in our POWDERPOST BEETLE CONTROL ARTICLE, wood flooring will many times include some cut of the tree which experienced insect activity at some point. But in most cases this activity is old and only adds to the "character" of the flooring. However, if you are seeing sawdust piling up on the floor as well as live insects, there would be cause for concern. Since most any wood floor will have some "holes" in random locations it's not unusual for some to be seen. But just how many do you see that look the same size and are they only now appearing? Also, do they look like they were finished over and that something is drilling through the finish the installing company applied?

Additionally, the quantity of activity you're seeing is important. Are we talking about 1-2 holes or 5-10? Again, this will all factor into the decision making process when the problem is assessed.

Provide more details and I may be able to further assist. But my instinct is telling me you may be looking at either old damage or a very finite few insects that are involved and in the end will die out and disappear. In either case no action would be worth the ordeal of replacing or treating since this is tedious and time consuming. But if have 10 or more holes with more appearing daily, some kind of action like the options we have detailed in the WOOD FLOOR TREATMENT section of our article may be warranted.

Here are direct links to the information I mentioned above:

http://www.powderpostbeetles.com/powderpost-beetle-control

http://www.powderpostbeetles.com/powderpost-beetle-control#wood_floor_beetle_treatment