Despite the bad reputation of mosquitoes, male mosquitoes do not bite, but harmlessly feed upon plant and fruit juices. It is only the females who require blood meals, due to a need for extra protein to produce eggs. In order to locate their victims, the females utilize a variety of cues, including sight, scent, and heat. From as many as 100 feet away, the insects are capable of detecting the scent of potential hosts, especially the carbon dioxide they exhale. Interestingly, mosquitoes are best at tracking the animals that are most profuse in their environment. Thus, those that inhabit areas such as the Arctic Circle are more apt to feed on native animals like polar bears or caribou, even if humans stumble into their ecosystem.