They are a common sight on some Michigan roadways - those white bumper stickers that say, "Don't Move Firewood. It Bugs Me!" They are a tongue-in-cheek way to remind Michigan citizens about the danger of moving firewood to different parts of the state and how it could carry the emerald ash borer (EAB) as an unwanted hitchhiker.

As summer vacation plans begin to take shape, the Michigan Department of Natural Resources (DNR) urges you to know Michigan's restrictions on the movement of firewood before you hit the road.

The emerald ash borer is an exotic Asian beetle responsible for the death of millions of ash trees in Michigan, and it threatens millions more. Following its discovery in 2002, the Michigan Department of Agriculture issued a quarantine for those southeastern counties infested with this invasive beetle.

Since then, MDA and its partners - the DNR, the United States Department of Agriculture, and Michigan State University - have learned a great deal about this pest's life cycle, its flight patterns, reproductive habits, and how it spreads.

They know, for example, that EAB has been artificially spread to at least 16 outlier sites through the movement of firewood brought from infested counties. Outliers are pockets of infestation found outside the affected counties.

The DNR asks campers to help protect Michigan's ash trees and leave firewood at home. The DNR urges all state park visitors to purchase their firewood locally, either from concession sales within the park or from private firewood vendors located around the entrance to the park. (DNR photographs by David Kenyon) Twenty-one counties currently are quarantined. They are: Branch, Calhoun, Clinton, Eaton, Genesee, Gratiot, Hillsdale, Ingham, Jackson, Lapeer, Lenawee, Livingston, Macomb, Monroe, Oakland, Saginaw, Sanilac, Shiawassee, St. Clair, Washtenaw, and Wayne counties.

The quarantine also includes 31 outlier sites. Visit www.michigan.gov/eab to learn more about the boundaries of the outlier quarantine.

Here's what people need to know to prevent the spread of EAB:

+ The quarantine restricts the movement of all ash trees, branches, untreated logs, and wood chips larger than one inch (in two dimensions).

For travelers heading to their favorite state park or state forest campground in the Upper Peninsula, firewood deposit boxes have been set up year-around near the Mackinac Bridge because it is illegal to bring deciduous firewood across the bridge. An EAB infestation was confirmed last September in Brimley State Park in Chippewa County. + Under the quarantine, do not move firewood taken from nonconiferous trees from any quarantined area into a non-quarantined area. Non-coniferous refers to trees that lose their leaves annually or non-evergreen species.

+ You may move firewood taken from coniferous trees such as pine or spruce (trees with needles).

+ All hardwood firewood movement from Michigan's entire Lower Peninsula into the Upper Peninsula, other states, or Canada, is prohibited.

+ You may move firewood of any species within quarantined counties as long as you do not pass through a non-quarantined area. For example, you may move firewood from Oakland County to Saginaw County.

+ It is illegal to move non-coniferous firewood from a quarantined area. It is punishable by fines and imprisonment.

Five things people can do to help stop the spread of EAB are:

1. Be aware of it; know what it looks like; report it if you suspect EAB is present in an area not already quarantined.

2. Understand the quarantine. Visit www.michigan.gov/eab for the latest maps, news and information on EAB.

3. Don't accidentally spread EAB to a favorite camping or recreation area. Don't move nonconiferous firewood. EAB larvae hide dormant under the bark and are undetectable until adults emerge in the spring and summer to lay eggs. It is the larvae that kill the ash.

4. Spread the word - not the bug.

5. If you inadvertently move ash wood, don't move it again. Burn it on site and report it by calling the EAB hotline at (866) 325-0023.

Several state parks and recreation areas have seen infestations of EAB over the past two years. In fact, park officials at Warren Dunes State Park in Berrien County recently removed 4,000 ash trees from the modern campground as the result of EAB infestation.

Movement of firewood is the fastest way to spread EAB, and the DNR asks campers to not bring

firewood with them to their favorite state park or recreation area. Firewood often is available for purchase at a state park or from residents who live near the park. The DNR encourages campers to buy their firewood from local sources where they camp.

Michigan has more than 700 million ash trees to protect from the EAB. Campers can do their part this season by leaving their firewood at home and purchasing it instead from local vendors.