Police said that current or former employees at the Philadelphia Insectarium and Butterfly Pavilion stole more than 7,000 insects, WPVI reported.
The heist, which police said happened on Aug. 22 and possibly other days, cleaned out approximately 90 percent of the insects, some of which are rare, the television station reported. CEO John Cambridge, an entomologist, estimated the insects' value at more than $40,000, The Philadelphia Inquirer reported.
Cambridge said he checked security cameras and saw employees using boxes and plastic containers to carry out insects, the Inquirer reported. Cambridge said he approached the employees and asked them to the return the bugs, waiting a day before calling police, the newspaper reported.
"These are young people," Cambridge told the Inquirer. "We don't want to see this follow them around for the rest of their lives."
Police have conducted searches but no arrests have been made, WPVI reported. Police said some of the insects, including a Mexican fireleg tarantula, have been returned, the television station reported.
Insectarium officials said they are hoping to restock their exhibit of insects in time for the Philadelphia Oddities Expo in November, WPVI reported.