Venomous black widow spiders were found in supermarket grapes at least twice this month, in Wisconsin and Pennsylvania-area chain grocery stores.

Black widows, which can be deadly, are known to build their webs in grape vineyards to catch insects. Since the 1990s, the iconic arachnids have occasionally found their way into supermarket produce, the Milwaukee Journal Sentinel reported earlier this month when it broke the news of a black widow in a bag of grapes from a Milwaukee-area Aldi supermarket.

According to the Journal Sentinel, Yvonne Duckhorn was shopping with her 4-year-old daughter in her local Aldi's produce section when she picked up a container of red grapes. As she examined the grapes in the container for mold, she noticed a spider moving amid the fruit.

"I saw the legs moving frantically," Duckhorn told the Journal Sentinel. "I've seen bugs on fruit before, and I thought, 'That is a very big spider.' Nothing I'd ever seen before."

Upon closer examination Duckhorn realized the spider had the characteristic red markings of a black widow. She took the container of grapes to store employees.

"I could tell she was a little nervous," Duckhorn said of the woman she gave the grapes to. "I told her the spider had red on it, and to be careful."

As a precaution, Aldi said it would pull all varieties of all grapes from its Milwaukee-area stories.

Earlier this week in Pennsylvania, Yvonne Whalen said she found a black widow in grapes she purchased at a Dillsburg-area Giant Food Store supermarket, the local ABC station WHTM reported Wednesday.

The black widow Whalen found was also in a bag of red grapes, though she had already taken then home and was washing them off when she found the spider.

In a statement, Giant said it was aware of the black widow found in Whalen's grapes.

"We regret that this incident has occurred and are taking immediate steps to prevent a similar incident from happening in the future. We will continue to diligently inspect product both at our perishable distribution center and at the store while thoroughly investigating this serious matter with our suppliers."

Click here to see a video of Whalen's black widow.