They’re in your hallway, outside your window and dangling from street lights. Urban spiders are becoming braver and bolder, it seems, with one species in particular evolving to no longer be fearful of light.
Dr Tomer Czaczkes, a biologist from the University of Regensburg in Germany, was inspired to investigate spiders and their attitudes towards light after a night-time stroll. “I was walking down a road one night, looking at all these fats spiders in their webs on lights, and I wondered: are they evolving to like light?”
His hypothesis was correct. A team of researchers used eggs from a common breed of spider (steatoda triangulosa) taken from urban and rural locations to see how they reacted to light when they hatched.
They found spiders from rural areas were less likely to build webs near light sources, whereas urban spider babies were totally up for it.
While many animals can lose out in human environments and suffer from issues like light pollution, some animals species are adapting to take advantage.
Researchers from the University of Regensburg and the Ludwig Maximillian University, Munich teamed up with Aarhus University, Denmark to conduct the study, based on a belief that urban spiders are big fans of building webs near light sources, at it helps them find food.
Dr Czaczkes said it could also be easier to survive inside buildings in the winter, “so spiders that don’t mind the light survive better”.
Professor Adam Hart, a biologist from the University of Gloucestershire, said the findings are unsurprising. “We humans are becoming a very powerful force in evolution and the adaptation of animals and plants to the environments we create, especially in urban areas, is only likely to increase,” he told HuffPost UK.
“Those spiders that are less averse to lights can take advantage of the fact that moths, flies and other insects are attracted to such lights. With plenty of prey flying into their webs, these spiders thrive and perhaps do even better than their light-hating neighbours.
“As long as their behaviour towards light is genetic, their offspring are likely to inherit that behaviour, and bingo – we end up with urban spiders taking advantage of the environment we create.”
If you do find spiders are increasingly coming into your house, don’t kill them. Prof Hart recommends just putting them outside. You can do this using the old glass and cardboard trick – simply place a glass over where the spider is (be careful not to trap its legs) and slowly slide a piece of cardboard underneath the spider so that you trap it in the glass. Then, take it outside and release it.