Arboretum News

Pest or Pollinator?

A cautionary tale with a happy ending.

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By Erin Buchholz, integrated pest management specialist

Integrated Pest Management Specialist Erin Buchholz takes a selfie with a caterpillar found in the Home Demonstration Garden. Photo by Erin Buchholz.

We are in the prime time of year for pest issues to present themselves. Plants and wildlife have a limited time to move through their life cycles, and the footprint for that kind of activity is quite noticeable for some.

My two eyes and short legs are no match for the 1,200 acres I need to scout for plant health issues. I’m lucky that I have wonderful co-workers willing to help me with that. I regularly get calls, texts and emails about some unusual things I need to check out.

A young quaking aspen in the Home Demonstration Garden is getting eaten by caterpillars. Buchholz says they would eat the entire tree if left to their own devices. Photo by Erin Buchholz.

Dave Stevenson is our Collections Curator and makes the rounds to do his job. He emailed some photos of plants that require my attention. In one, I saw a young quaking aspen (Populus tremuloides) in the Home Demonstration Garden that was covered in caterpillars.

A few leaf chewers are usually nothing to worry about, but caterpillar swarms can be devastating to a new tree or shrub. Not wearing my glasses, I couldn’t readily identify the species on the tree. Fearing gypsy moths or eastern tent caterpillars, I marched over and took a look.

Ted Pew, Landscape Gardener for the Home Demo area, said he remembered something called “velvet cloaks” on poplars in past years. That certainly narrowed it down for me. Upon confirming the ID with our Operations Director, Alan Branhagen, I had a name: spiny elm caterpillar.

Spiny elms are the caterpillar stage of the mourning cloak butterfly (Nymphalis antiopa), a long-lived species that overwinter as adults!

My job title of Integrated Pest Management Specialist makes people nervous. Some think I just kill insects indiscriminately to protect plants at all cost. Nope. I try to think how my use of insecticides, fungicides and other pesticides could impact the food chain.

Overuse of chemical controls has not only harmed our pollinator numbers, but bird numbers, too. Any action I take could have incredibly negative results for the wildlife that resides at the Arboretum. By poisoning one tiny critter, I could be poisoning larger and larger predators that we love to see.

Buchholz carefully picks the caterpillars off the tree, so she can transplant them to a new location at the Arboretum. Photo by Isabella Tecken.

However, the little aspen needed some protection. So, I grabbed a ladder and a bucket, shook off as many caterpillars into the bucket as I could, and handpicked the rest. I added some leaves from the sucker sprouts of the aspen so they had plenty of food, and we were off!

The swarm of caterpillars is transferred from the Home Demonstration Garden to the Dwarf Conifer Collection.

Stevenson suggested a mature quaking aspen in the Dwarf Conifer Collection (currently closed to the public) for their relocation. I found a nice twin-stemmed one, and propped the bucket on a couple of branches.

The bucket at the base of a larger quaking aspen that will be better suited to handle hungry caterpillars. Photo by Erin Buchholz.

Of course, it stormed that night. I worried they would not leave the bucket, in which case they might drown. Or maybe a predator would find them and be rewarded with a plethora of protein.

I went back in the morning, and the bucket was empty. I grabbed the long lens of my scouting camera, looked up to the top of the tree, and saw that the little ones made it.

The caterpillars appear to be doing well in their new home. They climbed about 25 feet to get to the top of the tree. Photo by Erin Buchholz.

Boasting unprofessionally to my coworkers, I spout, “Let it be known that when I say I’m all about pollinator protection, I really mean it.” They humor me, and nod in agreement.

No living thing on this planet gets to choose what species it is. The more tolerant we can be of the damage one causes, the less likely we are to harm something for which we truly care.

With a little luck, those caterpillars will transform into Mourning Cloak Butterflies. Photo by Dianne Jandt.

I will always try to protect plants. The Arboretum would not exist without them. But some damage is okay, if it helps out another living creature. Balance. Peace. Harmony. Be well, everyone.

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