You better watch your mail.

A German man has been arrested on animal smuggling charges after he allegedly mailed hundreds of live tarantulas to customers in the United States. Sven Koppler, 37, was busted yesterday when he arrived in Los Angeles to meet with an associate, according to investigators.

In announcing Koppler’s arrest, federal officials today released the above evidence photos (click to enlarge) showing some of the seized arachnids. A third photo (click here to view) shows dozens of baby tarantulas, each of which is enclosed in a color-coded straw corresponding to a specific tarantula species.

The federal probe of Koppler began in March, when agents intercepted a package headed for L.A. that contained about 300 tarantulas. Investigators subsequently seized a second United States Postal Service shipment containing nearly 250 live tarantulas. During an undercover probe (dubbed “Operation Spiderman”) run by U.S. Fish and Wildlife Service agents, Koppler allegedly mailed several other packages containing tarantulas.

Charged with one count of illegally importing wildlife, Koppler received about $300,000 via tarantula sales to buyers in dozens of countries. These purchasers include “approximately nine people in the United States,” according to prosecutors.

No telling what's in your mail.