Most people try to stay far away from hissing cockroaches, desert hairy scorpions, and venomous, six-eyed sand spiders. Not the team of thieves that hit the Philadelphia Insectarium and Butterfly Pavilion over four days in late August.

They made off with those critters and nearly 7,000 other insects, spiders and lizards — more than 80 percent of the institution’s collection.

John Cambridge, the facility’s owner and chief executive, said he and his colleagues first noticed animals missing from their enclosures. Then they discovered that a backroom used for storing scores of off-display animals contained empty shelves. At that point, Cambridge and his employees checked security camera footage.

“And then [we] just put our head in our hands for the next 12 hours as we put the pieces together,” he said.

In video from Aug. 22, five uniformed employees can be seen milling about the firelegged tarantula exhibit. One man, a museum director, opens the tank, scoops the spider into a small container and walks away. Less than a minute later, a group of visitors enters the frame, and the remaining four staffers return to work.

Other security cameras captured the employees loading some boxes into their personal vehicles and removing others via a fire escape. Philadelphia police have not named any suspects or filed charges.

“Movement of creatures throughout the facility is quite common,” Cambridge said. “We’re always taking things for education programs, doing maintenance, cage exchanges, and so they just walked straight out the front door with them.”

But why? Who would want 7,000 very creepy crawlies?

Plenty of people, it turns out. Cambridge said the exotic pet industry is “absolutely bursting with buyers right now.”

A healthy adult Gooty sapphire tarantula can cost more than $350, while Mexican fireleg tarantulas go for $250. Rhinoceros cockroaches are worth $500 per mating pair. According to a police report, the entire theft is estimated to be worth $30,000 to $50,000.

The fact that insects and arachnids are generally easy to transport and care for is part of what makes illicit trade in these animals so difficult to curb. These species can easily be sent in the mail, said Karen Verderame, who has spent more than two decades caring for live arthropods at the Academy of Natural Sciences of Drexel University.

“If you’re trying to ship a monkey, that’s a whole other story, right? But an insect, you can put it in a box with insulation and claim that it’s something else,” Verderame said. “Unless they have reason to open up that parcel, for all they know it’s what you say it is. It’s that easy.”