It was described as a senior prank, but not everybody was amused last week when intruders entered a Southern Maryland high school and released 72,000 ladybugs.

It happened Wednesday at Chopticon High School in the Morganza area of St. Mary’s County. Five people in masks forced open a door about 3:40 a.m. and released the insects,the county sheriff’s office said.

“It was a mess,” a school staff member said. “When you walked in the building, they covered the walls and hallways, flying around, and they were all in a pile in different areas of the building.”

He said vacuuming began at 6:30 a.m. and continued for hours.

Bags of vacuumed-up bugs went into a large trash receptacle, he said, but some insects lingered at the school through Thursday.

Five masked people broke into Chopticon High School in Morganza, Md., and let 72,000 ladybugs loose, allegedly as part of a senior prank. Suspects now face criminal charges and one student has been prohibited from participating in the graduation ceremony. (WUSA9)

The disruption appeared limited.

“I didn’t see a ladybug all day,” said a teacher whose class met on the second floor. The teacher said that students “thought it was funny” but that a couple of people were heard to say they “felt bad for the bugs.”

The staff member who described the cleanup effort said it “wasn’t quite that funny.”

According to the sheriff’s office, the insects were ordered by way of the Internet. The office said that four juveniles were charged with burglary and that three adults were also to face charges.

Ladybugs are small beetles that have spots on their red or orange wings. They have been made popular, in part, by a nursery rhyme that urges a ladybug to “fly away home.”