Sawdust under my wooden pillar?


Hi I live in a house built in 1960s. I have been living here for about 7 years. A few weeks ago I noticed some sawdust from the bottom of a wooden pillar on the first floor of the house. After I wiped it, a small pile of sawdust appears again in hours. I guess there is some insect inside the pillar? What can I do to solve this problem? Thank you in advance for your advice.

q sawdust under my wooden pillar
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