Fausse veuve et chauve-souris

A spider has been spotted killing and eating bats for the first time

The deadly bite of the black widow spider is feared by all arachnophobes. But because of this reputation, another species of spider is falsely considered deadly, even though its bite is not really poisonous to humans. This is the “false widow” Steatoda nobilis which can still transmit antibiotic resistant bacteria.

However, even if S.nobilis is not as dangerous as the black widow, it can still be a formidable predator. In an attic in Shropshire, Britain, a false widow was spotted trapping, killing and feeding on a mammal for the first time. The unfortunate victim was a bat.

According to the researchers, this is the first reported case in the world of an arachnid of the family Theridiidae killing a bat, and of a vertebrate killed by such a spider in Great Britain.

A disturbing finding

According to the researchers behind the observation of the spider’s unusual behavior, bats had taken up residence in the attic of one of their own in North Shropshire. During the spring of 2021, these animals were joined by a large false widow spider that weaved a web around the corner of an external fireplace mantle.

Early in the summer, the spider managed to trap a baby bat that was dead and wrapped in silk. The bat was also slightly shriveled, visibly eaten by the false widow. The mammal eventually fell off the web, but 24 hours later an adult bat was found in the same situation. The occupant of the house hastened to deliver the pipistrelle still alive. She returned to her perch.

The exact species of bats caught in the trap is not known with certainty, but it seems that they are part of protected species such as the common pipistrelle or the soprano pipistrelle. According to scientists, this is the second case of predation by S.nobilis on a protected vertebrate species. Although this kind of situation is rarely reported, the occurrence of such an event can be much more frequent than we think.

A potential new invasive species

In their article published in the journal Ecosphere, the authors indicate that S.nobilis continues to expand its range and increase its population density. We can therefore expect more species to end up as prey, including rare, threatened or even protected species.

Thus, the false widow spider deserves special monitoring to assess its impact on native organisms and its possible classification as an invasive species where it is most abundant.

SOURCE: IFLScience

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