Beware the jabbervarch culicivora, my son

African Spider Craves Human Blood, Scientists Find

Although many spiders have relatively poor eyesight - those that use webs to trap prey have no need for acute vision, Nelson says - jumping spiders are an exception.

'Salticids are predators that actively search for prey and mates and typically do not build webs,' she said. 'They have evolved eyes that support high-acuity vision suited to their active lifestyle.'

Spiders don't have the skin-piercing mouth parts needed to feed directly on human blood, but the mosquito-munching jumping spider appears to have got around this. The strategy has other advantages as well, Nelson points out.

'Blood-feeding is a dangerous activity,' she said. 'Animals that are bitten have a swatting response, and often the insect is killed.'

By eating mosquitoes, the spider avoids the risk of being squashed by an unwilling blood donor.

The study team suspects a blood meal is also biologically important to E. culicivora.

They say spiders expend a lot of energy breaking solid food down into liquid by injecting their prey with digestive enzymes.

'Perhaps blood is a ready-made, nutrient-rich liquid meal,' Nelson said.

I plan a moral triumph by posting this without a single joke about the resemblance between E culicivora and the contemporary conservative. And they're probably not either slithy or brilling.