By Jaclyn Cosgrove
From Los Angeles Times
LOS ANGELES—The hoot of a great horned owl. The munching of a mule deer enjoying grass. The crunching of your feet on the sandy soil. To any hiker, these sounds enhance the joy of being outdoors. But the endorphin rush of a great trail can be blunted by the high-pitched buzz of a mosquito hovering around your neck, trying to score some lunch.