Needing a base on the Pacific Coast in 1852, the U.S. Navy went searching for a site that was “safe from attack by wind, wave, enemy, and marine worms” (Lott 1954). The attack worm that worried the Navy was the native Pacific shipworm, Bankia setacea. Shipworms bore tunnels in wood, severely damaging wooden pilings and ship hulls.

The Navy built its base in the northern part of San Francisco Bay, where the water is too fresh for the Pacific shipworm. No enemies attacked until an Atlantic shipworm, Teredo navalis, which tolerates fresher water than its Pacific cousin, arrived in the bay. The Atlantic shipworm multiplied rapidly and proceeded in 1919 to bore its way through the available habitat, dropping wharves, piers, ferry slips, and other maritime facilities into the water at an average rate of one major structure every two weeks for a period of two years (fig. 1). In current dollars, the worm caused between $2 billion and $20 billion in damage.