Wildlife charities have branded the closure of schools affected by a false widow spider infestation an “over-reaction”.

Four schools - Star, Ellen Wilkinson, Rokeby and Lister - have so far confirmed that they will remain closed after the arachnids were found on their premises.

The infestations were both inside and outside the buildings, as well as in a number of locations across the school sites.

Two others - Monega and Earlham - closed for a day as a precaution while an investigation was carried out.

Earlham reopened today, while Monega will repoen on Monday. The nursery will, however, be closed until Monday, October 15.

Lawrence Bee, from the British Arachnological Society, branded the decision to close the schools a “massive over-reaction”.

“If they fumigate the whole place to get rid of the spiders they are going to get rid of other spiders as well, which are important,” he said.

He added that the way spiders breed meant they could move around with relative ease.

“When they’re young, they’re in sacs, and when the breeze catches them they can go with the breeze,” he said.

“They can travel quite a distance in this fashion.”

Conservation group Buglife has branded the decision to close the schools a “radical and unnecessary over-reaction”.

It said that despite false widows living in and around schools for years, it was aware of no incidents of a bite causing a significant health impact to a pupil, and that the spraying of insecticides could pose more of a risk.

Matt Shardlow, the charity’s CEO, said: “It is a shame that the education, and potentially the health, of these children is being harmed by this knee-jerk reaction.”

Dave Clare, who is the head keeper of invertebrates at the Zoological Society of London, said that false widow spiders were not uncommon in this part of the country.

“Spiders are active,” he said.

“It’s not that they’ve been distributed a lot more or they’re just spreading because of humans.

“False widow spiders are resident in the UK, and they’re relatively common in the south.”

Dave, who also runs London Zoo’s friendly spider programme designed to help those with arachnophobia, explained that although the spiders have been in this country since the 1800s, they have started becoming more obvious in the last 30 to 40 years.

“What can happen is that there’s a kneejerk reaction,” he said.

“People think they’ve got to get them before they hatch, but that’s not going to happen until spring, and the young ones aren’t able to bite.”

But the decision to close the schools was defended by councillor Julianne Marriott, cabinet member for education.

She said: “No headteacher wants to be in a position where they have to close their school.

“It’s our headteachers who know their schools best and they made their decisions because of the scale of problem in their school, after getting advice from pest control and carrying out a detailed risk assessment.

“We fully support their decisions and will work with them to support their children.”