An African pest that can cause illness and death in people and animals is the tse tse fly. This insect transmits sleeping sickness, when its bite becomes infected. For some reason the insect is attracted to the color blue, and Akagera National Park in Rwanda has set up more than a thousand black and blue flags to attract them. The flags have a chemical that renders the male impotent, and there have been no known cases of sleeping sickness in the park, either among visitors or the wildlife in the last six years. It is still a good idea for travelers not to choose blue for their safari wardrobe.