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Male black widows are terrible house guests, a new study found, because they destroy the webs of their potential mates — all with the aim of making females less attractive to rival males.
A female spider can get as many as 40 suitors crawling up to her web in a single night. By wrecking her home, a male can disrupt the message she is trying to send out about her age and mating history, which she communicates through pheromones and the shape of the web. Not that she necessarily minds the destruction.
"By reducing the web, the male is not only reducing his chances of competing with other males, he might also be doing the female a favor," Catherine Scott, lead author of the study, said in a statement.
"Web reduction may be giving her the opportunity to rebuild her web without pheromones and get on with reproduction, rather than wasting time and energy chasing away a parade of redundant male suitors."
The study was published last week in the journal Animal Behaviour.
Researchers from Simon Fraser University in Canada took female black widows and their webs from the lab to Vancouver Island, and waited for the male spiders to show up. They compared webs that were intact, damaged with scissors, and destroyed by male suitors.
The least attractive were the webs that were damaged naturally. That led the researchers to believe that it's not only reducing the size of the web that matters — male spiders could also be targeting areas rich with the female's pheromones or adding their own pheromones to keep others away.