The Dean Academy in the Forest of Dean, Gloucestershire, has identified a number of false widow spiders in the school's computer block, as well as other areas.
A letter to parents on the school's website confirmed that the school would be closed tomorrow.
Vice principal Craig Burns said the academy had taken immediate pest control advice on discovery of the spiders. The letter posted online today read:
We have identified an issue with false widow spiders in the academy in our ICT block and therefore took immediate advice from pest control.
We therefore made the decision to close the ICT block for the whole of today so that pest control could fumigate the area.
Unfortunately, during this afternoon there have been further false widow spiders identified in other areas of the academy.
The Dean Academy in Gloucestershire has written to parents to inform them of the schools closure tomorrow due to "an issue with false widow spiders in the academy".
The Dean Academy in Gloucestershire will be closed all day tomorrow, following an outbreak of false widow spiders.
The Academy said it had taken advice from the Health and Safety unit at Gloucestershire Local Authority and C & D Pest Control, Chepstow, to close the school.
One of the few spiders capable of biting humans, the false black widow, is "becoming more common and more widespread," according to an expert at the Natural History Museum.
John Tweddle of the Angela Marmont Centre for UK Biodiversity said that "populations have rapidly spread" and they are now found in many parts of southern England.
He said the spread of the species - which is related to the infamous black widow but is far less venomous - is at least partly a response to a changing climate.
One builder from Essex, who reportedly disturbed a nest of false widows at a school, had to have his leg sliced open and the venom flushed out, the Daily Mail reports.
The Devon-based footballer Steve Harris also had to have an emergency operation to remove the poison after he was reportedly bitten on his side.
A number of videos on YouTube appear to show the 'false widow' spider in action.
It was revealed today a mother in Northampton has escaped harm after she found a flesh-eating spider in her bed.
Donna Bradbury, who suffers from arachnophobia, spotted the poisonous false widow spider on her pillow, but managed to jump out of bed before being bitten.
- The spiders are usually coloured purple and black
- They feast on insects and sometimes other spiders
- Female 'false widows' lay up to 120 eggs at a time