On the pest chart not many insects out rank the mosquito. Throw in that they carry and spread disease throughout the globe and you have a pretty solid case for making them a public enemy. Enter Evarcha culicvora, a small spider that has specialized on dining on those flying phlebotomist's. Interestingly the spider is dining on the blood the mosquito holds, and does it for mate attraction as much as nutrition according the paper "Mosquito-specialist spiders".

From Fiona R. Cross and Robert R. Jackson's Article in Cell:
A mosquito specialist is a predator that actively prefers mosquitoes, by which we mean that it is differentially motivated to capture mosquitoes among possible prey. This would make it extraordinarily useful, as it would be targeting an insect that matters to people. At best, the mosquito is a nuisance and, at worst, it is a notorious disease vector. There may be many predators that eat a lot of mosquitoes, but experimental evidence is needed to show that a predator has the sensory capacity to distinguish mosquitoes from other prey and that it deploys a strategy of choosing this specific prey type. There is one predator for which the required evidence is actually available: its name is Evarcha culicivora (Figure 1), a jumping spider (family Salticidae) from the Lake Victoria region of East Africa.

Why does E. culicivora feed on blood?
Part of the answer is that indirect blood meals give both sexes of E. culicivora an odour that makes them more attractive to the opposite sex. For E. culicivora, it is as though blood is perfume, and it seems to be a perfume that needs to be continually replenished. For a predator that singles out mosquitoes, this might have interesting implications. For E. culicivora, killing mosquitoes appears to be motivated by more than hunger in the context of nutrition. Even when satiated, this predator goes on killing mosquitoes for perfume.

Being a spider with blood on its mind, E. culicivora became more than just an arachnid curiosity; E. culicivora's unusual behaviour appears to provide a handle on understanding selective attention.

What is so interesting about selective attention?
‘Selective attention’ is a term used mainly in cognitive psychology, whereas biologists tend to be more familiar with the term ‘search images’. Both terms are relevant when an animal becomes prepared to detect and identify something specific. The word ‘image’ in ‘search image’ implies that animals are using vision and there is, indeed, a strong bias in the search-image literature toward examples of visual attention. However, one of the more interesting things about research on E. culicivora is that this species lends itself to experiments on olfactory as well as visual search images. E. culicivora deploys search images in the context of finding prey and in the context of finding mates, with seeing a mate or a preferred prey triggering selective attention to the visual characteristics of mate and prey, respectively, and with smelling a mate or a preferred prey triggering selective attention to the odour of mates and prey, respectively. There is also evidence of cross-modality priming, with the odour or sight of prey triggering selective visual or olfactory attention to prey, respectively.

Full Text at Cell: Mosquito-specialist spiders

Also enjoy this high magnification image of the evarcha culicivora