Disclosed are water-soluble silver-amino acid complexes for preserving for wood and foamed resin construction materials where there is long-term retention of a preservative effect and the effect is retained with a low concentration. The silver-amino acid water-soluble complex is formed from 1 molar part silver and 1 to 3 molar parts amino acid (e.g., histidine, methionine, and N-acetylmethionine) and can be further combined with an insecticide (e.g., neonicotinoid based compounds such as nitenpyram, imidacloprid, acetamiprid, thiamethoxam, clothianidin, dinotefuran, and thiacloprid) to control termites.
