Manitowoc middle school closes after spider bites student and teacher

MANITOWOC, Wis. (CBS 58) -- Students and teachers at Wilson Middle School in Manitowoc, learned about the yellow sac spider the hard way after an encounter with them shut down their school. 

"We immediately sent something out with parents, it was near the end of the day," said Cory Erlandson, principal of Wilson Middle School. 

It happened Thursday, Dec. 8, when dozens of yellow sac spiders were discovered. A student and teacher were bitten, and the bites became itchy and swollen. The teacher required medical attention. The school was shut down so exterminators could come in. 

Monday, Wilson Middle School reopened. 

Experts say yellow sac spiders are not lethal, but their bites can be painful.

"If you get bit by one of these spiders you can have a reaction similar to what the student experienced, redness, swelling, pain, itching, but it's pretty similar to a lot of other things biting," said Erlandson. "They could have come in on something or whatever, possible, we don't know. We obviously would like to explore that." 

A statement from the Manitowoc School District says exterminators killed about 30 spiders.