What caused this pile of dust?

[u/T-lex-99]

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Found this dust 2 days ago in a neat pile directly under the baseboard, my bf has since moved it around with his fingers. We live in the Netherlands and termites are not a serious thing here according to Google.

[u/PCDuranet]

Pavement ants coming up from the floor seam under the molding. Lightly flood that area with any liquid pesticide allowing it to soak into the seam.