Tuesday, October 17, 2017

Searching for Sirex spp.

We are at it again, setting up wood wasp traps as part of a localized survey to detect native siricids and parasitoids.  A wood wasp native to Europe, Sirex noctilio, has been introduced to parts of the U.S.  For now, the non-native species has only been detected in portions of NY, PA, MI, and VT. Our southern pine species would be prime habitat for these critters though, so we are making attempts to detect the insect. 

 A ridgetop outside of Hot Springs, NC that was burned during fires in spring of 2016.

Our "Lincoln log" style wood wasp trap.

We scheduled our first round of cuts to coincide with typical flight times of local Siricids.  Of course we didn't realize we would be experiencing record high temperatures in October, lugging a chainsaw and gear up steep slopes...

 Moving a tree top off of a steep slope to position next to our trap setup.

Wood wasps love dead and dying pine trees, so we selected an area that recently experienced a stand replacing fire.  The challenge was finding live pine trees that aren't already being colonized.  We were able to find white pine, Virginia pine, and Table mountain pine trees in good condition.

Bud labeling and marking one of our traps.

A live Table mountain pine tree in a stand with mostly dead overstory.

We did this detection survey back in 2015/2016 on 2 different sites with white pine.  We did not detect any of the non-native pest (Great!), but we did not get many of the native siricids either.  The traps will sit out in the woods for approximately 9 months. Then, logs from the traps will be moved into rearing cages where we can monitor what comes out.

Wednesday, October 4, 2017


In a controlled experiment, as many variables as possible are accounted for, a hypothesis is conceived.  The experiment is carefully planned, laid out, and implemented.

 Aerial view of our hemlock restoration planting field experiment.  Photo credit Rob Nelson.

Weather stations and pendant sensors used at our field sites being prepped for launch.

Take all of that planning and equipment to the field however...

A temperature/RH sensor hides in this radiation shield that was knocked over and wire severed.

 A sensor set-up measuring temperature/RH and soil moisture knocked over and pulled up.

 A weather station pulled completely out of the ground.

A repaired radiation shield stayed put, but the pendant sensor was bitten and cast aside.

A temperature/RH sensor that was pulled apart and chewed.

This damage had occurred over the course of several months and we had our suspicions as to who was responsible.  


Thursday, June 29, 2017

Slinging more Silver flies this spring...

We have been at it again this spring with a new predator of hemlock woolly adelgid (HWA).  This is our third consecutive year releasing silver flies on HWA infested hemlocks.

A hemlock branch with both the fall (sistens) and spring (progrediens) generations of HWA.

You see, one of the more annoying characteristics of HWA is that they can produce two generations of offspring in one year.  A fall, sistens generation and the spring, progrediens generation.  The predator beetles that we are so fond of are only active during the fall, which means the adelgids have an entire season to feed and reproduce without the presence of a predator. 

Well, we aim to end that with the introduction of silver flies! 

Our work thus far is with two different Leucopis spp., argenticollis and piniperda.  Both of these species are native to North America.  The silver flies in the West, where hemlock woolly adelgid have been active for millenia, live on hemlocks and feed on HWA.  The silver flies in the East, where HWA has only been resident for the last 50 some odd years, do not live on hemlocks or feed on HWA. So, we are introducing a Western biotype of a native species in order to eat an exotic invasive pest.

I will spare you the lengthy details on permitting and logistics of such an experiment.  Just know that this involves a whole lot of people at several state and federal agencies making sure all that we do is upright and in-line.  We have an amazing cooperator in the Pacific Northwest rearing flies and sending them to us for our experiment.  The big idea in all of this is to establish biological control agents that are able to eat, harass, harangue, or otherwise subjugate HWA, so our hemlock trees can live long happy lives with only minimal damage from the pesky adelgid.

University of Vermont graduate student Kyle Motley readies branches to receive silver flies.

This years experiment is the largest yet with field sites from South Carolina to New York including Great Smoky Mountains National Park in Tennessee.  We are hoping for more positive results!

 A sleeve cage is mounted on an infested hemlock branch. 

We are releasing flies into sleeve cages on infested branches at our field sites, then returning at predetermined intervals to collect the samples in order to find out how well flies are feeding and reproducing. 

"Now here we go dropping science, dropping it all over..."
-Beastie Boys from "The Sounds of Science"

Wednesday, June 21, 2017

Let there be light!

Yep, the "daylighting" of hemlocks has finally begun!

A big thanks to Kenny Frick and Rusty Rhea with Forest Health Protection for bringing the big saw!

Did you see all that light come through the forest canopy?

Based on what we know from anectodal evidence in the field and research done in a nursery setting we can say that hemlocks in full sun tend to be healthier and have lower levels of adelgid infestation.  So, we are bringing that hypothesis to the big woods and trying out a new experiment.  This study has been on paper for quite a while and we have been scouting sites for the better part of a year. 

Basically, we are selecting relatively healthy hemlock trees of a certain size and "releasing" them to a full-sun environment.  Our experiment will test 2 different techniques along with other variables to see if increased exposure to light can help these trees stand up to HWA infestation. 

More details with better quality video and photos are coming!

Wednesday, May 3, 2017

Hope for the Hemlocks: Restoring Balance

A big thanks to Untamed Science for making this short film.  So many people and organizations throughout the country are working to conserve hemlocks.  There is indeed hope!

Tuesday, March 28, 2017

More predators in action!

Just last week we were collecting data for some ongoing research we are doing measuring the impact that predator beetles are having on hemlock woolly adelgid.  We saw evidence of predators on all of our trees, but I was able to capture this satisfying footage of a Laricobius nigrinus larvae feasting on adelgids...

Just how much of an impact are these predators having?  Not sure just yet, but we are part of a regional study hoping to figure that out.  Stay tuned...

Tuesday, February 28, 2017

Visiting The Smoky Mountains...

At the beginning of the month, Bud and I visited Great Smoky Mountains National Park to talk about a research project we would like to do there and look at some potential sites.  Driving through Gatlinburg, we were astounded at the damage caused by the wildfires this past fall on the park lands, but even more so the damage in downtown Gatlinburg itself! 

Like so many others, I followed the news stories as the fires were ongoing, but it is very different to visit.  People all around town are actively picking up the pieces and rebuilding.  These were devastating fires, a tragic reminder that we must be vigilant stewards of the environment we live in and ever aware of local climate conditions.

 Only the foundation and chimney remain of a house near downtown Gatlinburg.

  Fire damage in some of the hemlock forest on park land.

Our trip was productive and despite the damage caused by wildfires, there are still good sites with surviving hemlock where we can do the proposed research. We also got to see some of the largest living hemlock trees that I have personally had the pleasure of seeing.  These beauties were over 100 feet tall!  The foresters at GSMNP have treated over 250,000 hemlock trees!  Obviously, they are working hard to preserve this vital tree species. 

A mature hemlock stand at GSMNP.

On the way back to Asheville we had this view of the park.  Yes folks, despite the warm temperatures, it is still winter.  The lighter color along the mountaintops is indeed ice.

 A view of GSMNP from the Foothills Parkway.