Three current or former employees of the insectarium are the suspects, the Philadelphia Police Department said in a statement to the Times.
No arrests have been made, but police have contacted the suspects and are searching their homes in hopes of finding surviving insects, the Times says.
It is difficult to know which creatures were stolen because the thieves also stole the logs used by the pavilion to keep track of the insects.
“I really don’t think the perpetrators realize the severity of what they were doing,” he added. “We believe these were taken for the purpose of resale.”
The insectarium opened its doors to the public in February 2017. Because of the theft, it has closed the second and third floors of the pavilion until November.
The organization has started a GoFundMe campaign to help with renovations and to try to replace some of the missing insects, the Times reports.
The insectarium is aiming to have a replenished stock of creatures to participate in the Philadelphia Oddities Expo, on Nov. 3.