(Harrisburg) -- Today marks a special occasion for many Pennsylvanians. It's the opening of the state's two-week rifle deer hunting season. Hunting is a four-point-one billion dollar industry in the state. The Pennsylvania Game Commission says if hunters can find a deer's food sources, such as acorns, they should be more likely to find the animals. Executive director Carl Roe says he expects the deer population has to really search for food -- after a wet spring and flooding from Tropical Storm Lee. "Weather really had an impact on our acorn crop, better known as hard mast, throughout a large part of the state," he says. "That will make deer somewhat easier to pattern, if you can find some acorns, some beeches where the deer are feeding. But the reality is, deer will have a rough, rough fall and winter because of a lack of that hard mast." Roe says he expects deer populations to differ from one county to the other. He adds hunters should remember to wear harnesses when using their tree stands and should always remember to clearly identify their targets and what's behind them when taking a shot.