Pringle landowners warned about pine loopers

A steady stream of vehicles rolled down a dusty road near Pringle’s Beaver Creek Monday night. The dust they turned up blew east toward a grey and nearly-bare ridge which used to be covered in healthy green pines. For some it brings to mind the landscape-level change brought on by the mountain pine beetle in years past.
Last year landowners near the Pringle area began to notice the pine needles from the trees on and around the ridge begin to disappear. The culprit was the pine looper, a kind of moth that feeds exclusively on pine needles during its larval caterpillar stage. At a home near this defoliated ridge, these landowners came together to discuss this pine looper outbreak.
Dr. John Ball, a forester with South Dakota State University, has been surveying the area with a small team of others for the past year and has reported that they are back for another round of defoliating pine trees. The purpose of the meeting was to discuss what the pine loopers are, what they do, where they are being seen, as well as treatments options for the affected pines. Because this is the second consecutive year of the outbreak, there is an added likelihood that many pines will not survive continued defoliation.
Pine loopers are a native insect which are always present in the Black Hills; however, large outbreaks like the one being seen near Pringle are “relatively rare.” These outbreaks typically occur about every 50 years.
Due to the relative rareness, the literature and research on these insects is “scant” said Ball.
“We’ve read both papers over and over again,” said Ball.
This lack of information means they are also discovering new things about the pine looper. For example, it was believed that adult moths, which have begun flying a couple weeks ago as some are still emerging from the ground, were completely nocturnal. In their surveys, though, they’ve been coming across several during daytime sweeps. They also have been monitoring adult populations with light traps, which are set up in the area to catch the moths at night.
Many had questions about why the outbreak has ocurred or why it has taken place in that location. A good answer doesn’t seem to exist at this point, partly due to the lack of research and attention paid to the insects.
“You got it here because you’re bad people,” joked Ball, before answering earnestly that there’s not a way for them to determine why the outbreak has ocurred now or in that location.
“The one question we won’t be able to answer is ‘why here?’” said Ball.
The eggs these moths are laying on the pine needles are now hatching into caterpillars—the defoliating stage of the pine looper. Just after they hatch, when the caterpillars are at their smallest is the best time to manage their potential impacts.
“When they’re little, they’re easier to kill, and  they haven’t done a lot of damage yet. That’s why you want to do the treatments early, rather than ‘revenge spraying’—spraying them after they’re done feeding,” said Ball.
It is recommended that any treatments be applied as soon as possible for this reason. The caterpillars are getting larger by the day—their appetites and subsequent defoliation grow with them.
In a span of just six weeks they go from newly-emerged caterpillars to fully-grown defoliating machines, eating all they can.
“The reason we’re having the meeting now is because it’s within the week. That’s why we’re here,” said Ball.
“The bigger they are, the more they eat. So, right now you have a good window to get out there and do any treatments should you wish to do so,” said Ball.
These treatments should also be done to individual trees rather than at a landscape level. This is for several reasons.
First, there is no guarantee that the trees will die from the defoliation. In fact, spraying will act more as “an insurance policy” or to “give them a little edge” said Ball.
“We’ll do individual trees—your key, most atheistically valuable trees,’ said Victor Gust, who was present with Warne Chemical to inform landowners on some treatment options and chemical products. He said they usually wouldn’t expect someone to spray even 50 trees.
Second, because they are a native insect, they have plenty of natural controls on their population levels.  Spraying for the pine looper also kills some of these natural predators.
“Nature has a way of managing this; we’re just going to tweak it a bit,” said Ball.
“We’re already equipped with all kinds of natural controls that are going to rapidly bring the populations down,” said Dr. Kendra Schotzko, an entomologist with the Black Hills National Forest. Some of these controls include wasps, diseases and parasites.
“We’re already seeing those natural controls build up,” said Schotzko.
This means that many of them will die without anyone needing to do anything. Last fall, many reported hundreds of dead pine looper caterpillars, causing whole areas to reek with the stench of their decay.
“It just hit you like a wall—the smell of dead caterpillars covering the forest floor. That’s a really positive indication of this natural process running its course,” said Schotzko.
Lastly, they don’t want to wipe out the pine looper population completely. Working with those natural killers of pine loopers, the goal is to knock the population down enough to minimize defoliation impacts on the most valuable pines to landowners.
For those who want to treat their pines without the assistance of professionals, don’t buy chemicals labeled for just any caterpillars. Having the proper equipment is also a must to be able to get to the tops of the trees. Should landowners choose to spray their favorite pines, the chemical should be applied from the ground with the appropriate equipment.
“Read and follow label directions,” said Ball. Using just any chemicals may not be effective and may even do more harm than good.
Although defoliation causes some trees to look dead, many will still live, but some may also die. Ball said there’s no way to determine “winners and losers” at this point of the outbreak.
“Two years of defoliation can seriously stress the tree. It does not mean instant death,” he said. “Oddly enough, there are some trees out there that there are going to be just fine. In fact, they’re going to thrive.”
Recent rainfall has been good for tree health, helping them to recover from past defoliation. Whether or not they are healthy enough to survive a second round will be anyone’s guess.