Drywood termites commonly enter structures through attic or foundation vents, or under eaves or shingles. Unlike subterranean termites, they don’t require a connection to damp soil, so they don’t construct mud tubes over concrete.
The appearance of tan to reddish-brown fecal pellets that look like coarse sand is typically the first sign of infestation.
Renowned entomologist (and 2003 PMP Hall of Famer) Dr. Walter Ebeling tested various dusts available during his time, including chlordane, dieldrin, sorptive clays and silica. He found that silica dust killed drywood termites within 90 minutes, and even an extremely light coating on wood blocks could prevent them from feeding. Because of this effectiveness and its lack of breakdown even in extreme heat, he recommended preconstruction wall void treatment, as well as post-construction dusting of attics and crawlspaces with silica dust to prevent drywood termite infestations. Localized existing infestations can be treated by injecting dust into galleries and tunnels, whereas broader infestations typically require fumigation.