From Colorado Public Radio (Michael Sakas):
The State Forest Service does a yearly flyover to track and map the damage. Dan West is an entomologist with the state, and said one notable finding from the 2018 survey is the continued spread of the spruce beetle. ..
The bug is different from the mountain pine beetle, known for its damage to lodgepole pine. West said the spruce beetle has been the most widespread and destructive forest pest in Colorado for seven consecutive years.
“About 40 percent of our spruce fir forests have been affected by spruce beetle since the year 2000,” West said.
The most damaged areas are in and around Rocky Mountain National Park, and parts of the San Juan Mountains, West Elk Mountains and the Sawatch Range. West said record-warm temperatures and record-low precipitation help the beetle thrive.
“That means there’s much fewer water resources that are available to these trees, which they use as a defense mechanism against attacking bark beetles,” West said. “So if it’s warmer and dryer in the near future, those prolonged drought events and warm periods cause these bark beetles to emerge earlier, have longer periods to be able to attack trees, and have fewer defenses that they’re fighting.”
From TheDenverChannel.com (Jackie Crea):
Currently, it’s the spruce beetle hitting the trees the worst. The spruce beetle is responsible for the death of more spruce trees in North America than any other natural agent. Lester and his team just finished studying the health of our forests and mapping out how much bark beetles have gotten to. He told Denver7 more than 5 million acres have been damaged.
“If you look at these beetles, most of them are native. And what kept them in check historically, is really cold weather,” said Lester.
Warming temperatures keep more bark beetles alive, he said. They burrow inside the trunks, blocking water from the tree, ultimately killing it. The problem multiplies because more dead brush leads to more wildfire fuel.
“…When they do burn, they’re really hard to manage and hard to predict their fire behavior,” said Lester.
Wildfires, in turn, bring other dangers, as they can move the soil, affecting our resources.
“If you’re a water utility, you’re gonna be filling your reservoir with silt instead of water, so we need to look at the areas that are more susceptible and focus our efforts there,” said Lester.
So how do we manage them? Lester told Denver7 it starts with this study, then spreading the word. They also help private landowners take care of their own trees, too, because the forest service can’t do it all alone.