Indoor Pest Control - Mysterious powder-bug??

we found scattered power droppings from our newly purchased hardwood dinging table.See link for pictures. We treated the table bottom side with pest control sprays and sealed all the gap with clear caulking.The powder still shows up every morning.HomeDepot told us termite doesn't like hardwood. What is it then?
Please help us to solve the power problem.It is driving us crazy!.

http://mytempphotosite.shutterfly.com/#n_19

For some reason,the picture link didn't show up.
here it is
http://mytempphotosite.shutterfly.com/#n_19

Here is a possible cause.

The carpenter ant hollows out wood to create nests called galleries. Though they do not eat the wood, the boring activity can lead to structural damage in wood components. The by-product of the boring is called frass and looks similar to sawdust or pencil shavings. Frass is the most common evidence of carpenter ant infestation.

Key here is "newly purchased". Most wood furniture is imported from places like Indonesia, South America and similar. Its infested with some sort of wood boring insect...get it out of your house and get it replaced by the selling store before they get into anything else.

Nothing you spray on it will work, it would need to be frozen or vacumn treated most likely.

When I was in The Navy, we weren't allowed to bring back most wood carvings and such for just this reason. Or they had to be stored in the ships freezers for a specific length of time.

Thanks for all the great advice! I have contacted the furniture store and told them about the infested furniture. I'll find out more what they gonna do next week.
Thanks again!