BOZEMAN, Mont. -

Officials with the Gallatin National Forest are cautioning spring firewood collectors to watch out for pine beetles.

New firewood permits are available April 1st.

Officials say Lodgepole and Ponderosa pine could contain the beetles and if they're brought back in wood the beetles could spread.

City officials say you can lower the risk of spreading pine beetles by only cutting trees that have been dead a two years or more.

As a rule of thumb, trees without any needles on their branches are free of beetles.

"A tree that's been attacked by a mountain pine beetle has...they're called pitch-tubes and it looks like popcorn balls are all over it. Those are trees not to bring into town, especially if they're green or they have orange needles on them," says City of Bozeman Forester Ryon Stover.

Bozeman officials say they have preventative measures in place and are working to fight pine beetles in the city.