Thanks for your question. Without a picture of an insect that might be causing this, I don’t have any idea as to a guilty party.   Please keep an eye out for any crawling type of insect. Whatever you see, snap a picture of it and send to us. With that information, I’m sure we could help you. 
Thanks for consulting with us.

Thanks for your response.  You are absolutely correct.  I am not sure it is insect related.  I mentioned that only because you were wondering if these trails might be due to an "bug" living in the wood.  In fact, these "trails" may not be attributable to anything living.  What happens if you try to remove them by detergent and scrubbing? You may want to try that and see if they reappear in a short period of time. 

Thanks again for consulting with us

Thanks for your response.  It appears that various challenges are facing you.

With respect to those tracks on the floor, I'm wondering if they are just part of the  wood and have nothing to do with any insects?

Pictures of any invading critters would be welcomed.

Good luck.  Thanks for consulting us.

Thanks for your thoughts.

While I have often seen insects scurrying around on wooden floors, rarely would they be inhabiting the floor itself.  Now if the floor was rotting, which doesn't appear to be your case, then insects might thenbe found within the wood.  A suggestion:  next time you scrub the floor, apply some Murphy's Oil to the surface and see if these tracks reappear.  Murphy's Oil is a great protective finish for wood floors.

Good luck.  Please keep us informed.

Glad to be of assistance.  Have a pleasant afternoon.  Thanks again for consulting us.