MANITOWOC (WLUK) -- Classes were canceled at one Manitowoc school Friday after a student and teacher were bitten by spiders.
Superintendent James Feil says classes at Wilson Middle School were dismissed early on Thursday after the student was bitten. Feil says the student brushed the spider off, but the bite area did become itchy and swollen.
The teacher who was bitten needed medical treatment.
"We immediately recognized that we had to address that," said Feil.
Exterminators were called in and have killed more than 30 yellow sac spiders, as of Friday morning.
Feil says most of the spiders were concentrated in an area near the library. They were also found in some classrooms.
He says, as of Friday, only two bites have been reported.
"We believe, you know, that probably the matter has been resolved, although we're just making sure that if anyone was bit, we want them to be aware of what happened."
A letter was sent to parents, telling them to watch for symptoms.
"There's redness, and it's a round distinct area, or there's two sort of tiny punctures in one place," said Dr. Suzanne Havican, family physician with ThedaCare. "It often is itchy."
Havican says yellow sac spiders are common in the area.
"These can cause a little bit more tissue irritation," said Havican. "Some people can get a lot of swelling and a lot of nerve pain."
According to Michigan State University, yellow sac spiders may bite humans more than any other spider.
They're often found in corners of walls and ceilings. The spiders tend to blend in with light- or neutral-colored walls because of their pale color.
"Of the house spiders -- it falls in the house spider category -- they're a little more aggressive," said Havican.
She says if you think you've been bitten, to get it checked out.
School officials hope this is the end of the issue.
"My senses is that there was such an immediate response that we have resolved this matter and we will be back in school," said Feil.
Classes are expected to resume on Monday.
The school district says the buildings and ground staff are investigating the source of the spiders.