Items on a typical thief's wish list: cash, jewelry, TVs, and other electronics. Heirloom silverware, maybe.

But a Gooty sapphire tarantula?

The exotic blue spider is just one of thousands of crawly creatures missing from the Philadelphia Insectarium and Butterfly Pavilion, chief executive officer John Cambridge said. Philadelphia police said they were looking at three current or former employees as suspects in the heist. Cambridge, an entomologist, estimated the critters' value at more than $40,000, speculating that many were destined for resale to collectors.

The museum director said some creatures seemed to be missing on Aug. 21, but he was not immediately sure if anything was wrong, as the insects, scorpions, and other specimens are sometimes moved between the exhibit space and breeding colonies in the back, or taken out of the building, in the 8000 block of Frankford Avenue, for traveling educational shows.

Then he checked the security cameras, and saw employees carrying out bugs and lizards in plastic containers and boxes over the course of several days, he said. Still, he waited a day to call police, first approaching the employees to request the return of the stolen animals.

Cambridge said he did so in part because some of the creatures did not belong to the museum, but were being held temporarily at the request of federal authorities who had seized them on suspicion that they were illegally imported. That means the potential for serious felony charges, he said.

"These are young people," Cambridge said. "We don't want to see this follow them around for the rest of their lives."

One employee gave back a few creatures, including a Mexican fireleg tarantula, but that was it, Cambridge said. He added that there may be an "emotional" component to the theft, as he found blue employee uniforms hanging from knives that had been thrust into a wall. Police are now on the case.

The museum opened in early 2017, at the former site of a much smaller bug exhibit run by an exterminator.

More than 7,000 bugs and other creepy-crawlies were taken from the museum, but that number is somewhat misleading. Many were roaches and other insects that the museum was raising to feed the stars of the exhibit. Still, they were crucial to the operation, and their loss has dealt the 18-month-old museum a serious blow, he said.

Among the display species stolen were giant African millipedes, leopard geckos, orchid mantises, and scorpions, Cambridge said.

For now, he plans to shut down the second and third floors of the building, keeping the first-floor butterfly pavilion and gift shop open. The full museum will reopen Nov. 3 with an event called the Philadelphia Oddities Expo, featuring special presentations and a tattoo parlor.