species of the day: Evarcha culicivora

http://www.pnas.org/cgi/content/abstract/102/42/15155

Spiders do not feed directly on vertebrate blood, but a small East African jumping spider (Salticidae), Evarcha culicivora, feeds indirectly on vertebrate blood by choosing as preferred prey female mosquitoes that have had recent blood meals.
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When presented with two types of size-matched motionless lures, E. culicivora consistently chose blood-fed female mosquitoes in preference to nonmosquito prey, male mosquitoes, and sugar-fed female mosquitoes (i.e., females that had not been feeding on blood).

http://www.nytimes.com/2005/10/18/science/18obse.html?pagewanted=print

The spiders are found in mud houses in parts of Kenya and Uganda that border Lake Victoria. Those houses tend to be very dark, said one of the researchers, Ximena J. Nelson of Macquarie University in Sydney, Australia, and jumping spiders need a lot of light to see. "That leads to the question of why they are here," Dr. Nelson said. "There must be some kind of prey that's of interest to them."
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Once it chooses its prey, the spider jumps on it and injects a paralyzing venom followed by digestive enzymes. Then the spider sucks up the fluids. Juvenile spiders, which are far smaller than the mosquitoes, jump on their victims from underneath; then they hold on for dear life while the insect flies around for a minute or so until the venom takes effect.