You've packed the tent, sleeping bag and pillow.

Thrown in some water, something to eat, maybe some marshmallows for roasting on the fire.

But whatever you do, don't bring your own firewood to a South Carolina state park campground.

The wood might harbor invasive insects and diseases that could threaten parkland forests and nearby wooded areas.

"It seems so innocent, but the insects that bore deep into the wood, or diseases carried on the wood, can get into the parks and wreak havoc," said Phil Gaines, director of the S.C. State Park Service.

"We want our visitors to enjoy their traditional summer campfire, their annual family camping, fishing and canoeing trip, but we want them to know there's a better way to handle the firewood," he said.

Park officials are trying to prevent a recurrence of the challenges already being faced in the Upstate at Table Rock State Park in Pickens County and Mountain Bridge Wilderness Area in Greenville County.

The woolly adelgid aphid has invaded hemlock stands in the two state parks. The egg sacs of these insects look like the tips of cotton swabs clinging to the branches' undersides.

Hemlock, a common, slow-growing conifer, provides food and shelter for a variety of wildlife, including deer. The tree's slow destruction can change the balance of the forest ecosystem.

The insect was accidentally introduced to North America from Asia in 1924. The pest now has spread to

11 eastern states from Georgia to Massachusetts, causing widespread mortality of hemlock trees. Fifty percent of the geographic range of eastern hemlock has been affected.

"They are very hard to treat," State Park Service spokeswoman Dawn Dawson-House said.

Park officials are applying a pesticide to the branches to kill the aphids, as well as performing soil injections and trunk sprays, she added.

"We are definitely not burning," she said.

Another reason not to move firewood around includes the spread of laurel wilt fungus in the lower part of South Carolina. It's brought in on the legs of beetles and affects red bay trees. The primary area of concern is Hunting Island State Park in Beaufort County, Dawson-House said.

The State Park Service also is trying to prevent the emerald ash borer from finding its way into the state. The beetle, which also is native to Asia, is highly destructive to ash trees, she added.

The Park Service has joined a national awareness campaign called "Don't Move Firewood" to help spread the word.

Posters went up before the Memorial Day weekend, and park rangers can sell firewood to visiting campers or suggest where to purchase wood locally.

Dawson-House said a bundle of seasoned wood will sell for $4 to $7 and be comparable in price to that of local hardware and grocery stores.

"The best thing to do is to purchase wood from the park rangers or from wherever the park ranger recommends," she said.

When people reserve a campsite with a ranger or online, they will be informed of the firewood policy and should check to see if the park offers firewood or not.

If someone shows up with firewood from somewhere else, rangers will inform them of the policy and suggest they not use the wood.

"It's an awareness program," Dawson-House said. "We don't have the resources to enforce the new policy, but our experience with our visitors has always been that if certain practices negatively affect the parks, they will do what it takes to preserve them."