Ladybeetles to the Rescue

An Unexpected Solution

For years, we at the RMF have watched the seemingly inexorable decline of the hemlocks, rooted in the rocky soil around Ragged Mountain’s Main Cliff. One by one they fell victim to Hemlock Woolly Adelgid, Adelges tsugae (HWA) and there was nothing to be done… or so we thought.

This summer I was contacted by Derin Tanyol. She and Peter Cody, Chair of the Gunks Climbers Coalition, had visited Ragged and while enjoying the climbing, were troubled by the sorry state of the remaining hemlocks rooted in and around the Main Cliff. Derin, who had done some research into the matter, wanted to connect the RMF with Carole Cheah Ph.D a research entomologist working for the State of Connecticut. Dr. Cheah’s work centers around the use of ladybeetles, Sasajiscymnus tsugae, to reduce populations of HWA.

Intrigued, I reached out to Dr. Cheah. While the idea of introducing a non-native species was initially troubling, Dr. Cheah quickly allayed my concerns with a knowledgeable enthusiasm that was hard not to get caught up in. Her extensive research into Ladybeetles, (not to be confused with ladybugs,) as an HWA mitigant in Connecticut goes back to 1995. Ladybeetles, it turns out, are the natural predator of HWA in Japan, and over twenty years of CT based study has not seen their feeding behavior change. When the HWA is gone, the lady beetles simply die off without detriment to native species. Further, Dr. Cheah told told me that the time was just right in the HWA seasonal life cycle for a Leady Beetle release and offered to come to Ragged and help with the dissemination.

Convinced, I went ahead and ordered two colonies of ladybeetles from Tree-Savers, a Pennsylvania based ladybeetle breeding lab. While I found the concept of mail order beetles somewhere between humorous and frightening, (think opening a box and having insects get all over one’s house, car, face, etc.) they actually arrived neatly packed in plastic containers wrapped in a foil-bubble-wrap to keep the light out. After an overnight stay in a cool part of my house it was off to be released. Thus on an overcast Friday in July, I met Derin, Peter and Dr. Cheah at Ragged.

Walking below the Main Cliff, we at first saw few signs of HWA. The live hemlocks looked well and the dead were beyond helping. Then, Dr. Cheah called us over and showed the needles of an affected tree. The white, cottony buildup seemed so small, looking more like a mild irritant than the killer of trees that have stood for hundreds of years. HWA, Dr. Cheah explained, feeds on the sap at the base of the needles, causing the needles to turn color and fall off. Without needles, the hemlocks lose their ability to photosynthesize and ultimately die.

Opening one container of ladybeetles, Dr. Cheah used a soft brush to coax the tiny insects onto a sprig of hemlock which we then clipped onto the branch of a nearby tree. We would come back and remove the clip later but this allowed the tiny insects to make their way to the HWA without us having to place them individually. Walking along the undercliff trail and then up the north gully, we carefully deposited other collections of beetles, sometimes using a sprig of hemlock, other times clipping on the plastic containers they came in, where they would have plenty of HWA to eat and be most affective.

Ladybeetles moving to their new home

The plastic container the lady beetles came in temporarily clipped to a HWA infested hemlock branch.

As we set the insects to work, Dr. Cheah explained that due to the life cycles of ladybeetles and HWA, it would likely take multiple years to achieve noticeable change. That said, she excitedly pointed out that despite the HWA resurgence brought on by the warm winters of 2020 and 2021, and the state of drought in much of CT for the past decade, the younger hemlocks at Ragged were still showing signs of healthy growth.

All our ladybeetles released at last, we stopped atop the Main Cliff to enjoy the view. The work took less than two hours but the result, be it realized in three years or thirty, will ensure that the hemlocks at Ragged stand tall for generations to come.

If you would like to learn more about ladybeetles and HWA here is a link to an article by Dr. Cheah, including a snippet about the release at Ragged.

Special thanks to Derin Tanyol her persistence in finding a solution when we thought there was none, to Dr. Cheah for her willingness to come out to Ragged and guide us through the release and to Peter Cody for taking the time to support another LCO.