Alexis Neiers of E!'s Pretty Wild fame was just arrested for a probation violation and authorities say she was in possession of black tar heroin when busted.

Neiers never checked in for probation after being released from jail in July (always a smart move), so this morning, cops decided to visit her at home.

Black tar heroin, an extremely potent form of that drug, was discovered on the premises, and immediately Neiers was placed under arrest as a result.

Alexis Neiers is still on probation for burglarizing celebrity homes in L.A. last year, so this new arrest could lead to some serious time in the slammer.

She was also found with a fake Florida driver's license and was booked on a probation violation, possession of a controlled substance, and perjury.

Forget using heroin ... all you have to do is check in with the probation officer, Alexis! How hard is that? You KNOW they'll look for you otherwise!