To corroborate my opinions about salt and chlorine, I consulted with zoos and veterinary hospitals. Neither adds salt to the diets of the birds in their care. This method does seem to work, with no obvious ill effects to the birds, but we would appreciate your opinion about its safety. Wynn and Mike Wright, Salt Lake City, Utah. But your question about diatomaceous earth adds a new wrinkle that deserves an expanded answer.
Diatomaceous earth is a fine powder composed of the shells of microscopic aquatic organisms.
These shells are made of silicates, the same general stuff that makes glass. Because the shells have so many sharp points and edges, diatomaceous earth has abrasive properties that make it useful as a buffing compound and a pesticide. When sprinkled in areas over which insects crawl, the diatomaceous earth will scratch the insects' protective shells. Through repeated scratching, the insects lose enough water that they die of desiccation. Some birds cannot handle the tiny cactus spines known as glochidia, and others cannot tolerate the stinging spines of certain moth caterpillars.