Trees infested by the pine beetle don't show they are dying until a year after infection.
Now that year has passed and the number of trees changing color in the hills could spell big trouble.
Experts say the beetle battle could be a larger problem than previously thought.
Marsha Davis loves living in the woods.
"We value the ecology the forest provides to wildlife that live there as well as the aesthetic value," said Marsha Davis, a Geologist.
While she loves the forest, she wasn't sure she wanted to pay to protect it.
"We had considered letting nature take its course and then kind of shifted our focus to whether the economics of that option versus spraying and decided it was more wise to put our money up front for preservation," said Davis.
Preservation in the form of spraying, an important step to battle the beetle.
Frank Carrol, a Forest Advisor, says the plight could be more widespread than previously thought because trees that were infested last year are just beginning to die.
"All of a sudden we're waking up and we are seeing whole hill sides that are covered with yellow green trees and we are starting to understand the infestation this year may be worse than anything we've seen so far," said Carrol.
While the trees marked with blue have already been protected, it's more than just spraying. It's about maintaining a healthy forest that will look like this for years to come.
"Where there used to be 30–70 trees per acre, we now have in some cases 10,000 trees per acre. And that's simply not sustainable," said Carrol.
Not sustainable and something that requires immediate attention.
Carrol says although spraying is the first step in the beetle battle, there are many other ways to maintain a healthy forest; including logging and thinning.
"We need to do a lot more and I hope people will start to respond to this because it's not too late," said Carrol.
While there is a lot of work to be done, it's not too late to take the first step and spray to keep the Black Hills beautiful.
"If all of us work on one backyard at a time, then we'll have a tremendous impact on what happens," said Carrol.
Carrol says it's not too late to spray.
There's still about three to four weeks until the beetle's take flight.