Talk about bad breath. When a goat exhales on pea aphids living on alfalfa and other plants, the insects fall to the ground  en masse. The aphids don't want to be lunch, but until now researchers weren't sure what caused them to drop. Perhaps it was the herbivore's shadow that scared them, or maybe the creature inadvertently shook them off. A new study, however, published  in tomorrow's issue of Current Biology, finds that it's the heat and the humidity of the goat's breath that the insects are responding to. When the researchers blew carbon dioxide or other components of human and herbivore breath on the aphids, the insects stayed put. But when they blew hot, humid air on the aphids, nearly two-thirds jumped ship. The team says that a number of other insects may employ this curious method of self defense.
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