Earlier in the program, we reported on the measures the Duluth Zoo is taking to protect its animals against the West Nile virus. Although the human risk of contracting the virus through a mosquito bite is small, it's added incentive to keep mosquito bites to a minimum. Jeff Hahn is an entomologist with the University of Minnesota Extension Service. Hahn says there are a number of natural mosquito repellents on the market, ranging from lemon grass to peppermint. But he says their popularity far outweighs their effectiveness.