Representatives of the silk industry approached Pasteur to ask for his assistance with a problem. The silkworms on which the industry relied had been attacked by a mysterious disease; its rapid spread threatened the whole of French silk production. Pasteur accepted the challenge, though he knew nothing about silkworms. For five years he worked on silkworm diseases along with other experiments. He eventually found what was at the root of the problem: a microscopic parasite (an organism living within another organism) that was killing the silkworms and affecting their food, mulberry leaves. His solution seemed quite drastic at the time, but it too worked: destroying all the unhealthy worms and starting with new cultures. The silk industry, very important to the French economy at the time, was saved, and Pasteur's reputation grew.