It’s nothing less than an invasion. Interlopers are coming into California by land, by sea…and by FedEx. That’s what happened with the European green crab, a voracious cannibal that stowed away in packages of worms sent by overnight delivery to commercial fisherman in California. Unknown to anyone, the tiny crustaceans were concealed in seaweed that wrapped the cargo and were freed into the Pacific when fishermen tossed it overboard. … California spends $3 million a year attempting to eradicate nutria, a large, homely, orange-toothed rodent that destroys wetlands and bores holes into levees. Another $3 million a year goes to educating boaters about quagga mussels, which hitch rides on hulls and cling to equipment in the state’s vast water transport system.  And, for the last 20 years, authorities have spent more than $34 million to manage Atlantic cordgrass in the San Francisco Bay-Delta.