Josh Hafner | USA TODAY

Police said it was an inside job: Whereabouts of some rare insects, lizards and snakes, including the venomous six-eyed sand spider, remain unknown — some 7,000 creatures missing in all. Their theft last month from the Philadelphia Insectarium came after security cameras caught employees moving boxes of critters out of the facility, its owner told CNN.

"I'm not sure there's ever been a larger live-insect heist," John Cambridge, the owner, told the network Wednesday. "Our insurance doesn't cover this. Why would they? This is unprecedented."

Missing creatures include zebra tarantulas, desert hairy scorpions and red spot assassin bugs, according to CNN. The New York Times adds more to the list: Giant African mantises, tiger hissers and domino cockroaches also disappeared.

The thefts of the animals, at least 80 percent of the facility's collection, occurred during the week of Aug. 20. Their total value amounts to more than $40,000, Cambridge told multiple news outlets.

The owner said he believes the crime was financially motivated, according to Gizmodo.

"“They are not difficult to sell, and there’s a thriving market of insect enthusiasts," he said.

While no arrests had ben made, according to the Times, police visited the homes of three current or former employees and recovered only a few of the creatures, including a Mexican fireleg tarantula.

The museum set up a GoFundMe, "Save the Philadelphia Insectarium," to raise funds to replace its collection and continue its efforts to "bring insects and other arthropods to the public in a way that they can be loved and appreciated."

The museum announced return of its fireleg tarantula on Facebook last week.