Late last summer I noted in this column the observation of far more purple loosestrife than in years past; some of you concurred. I knew that there had been a biological control in place in the Northwest Corner and the thought, “Is the biocontrol no longer working?” nudged me from time to time over the winter.
Biocontrol is the science of enlisting a natural predator to control a plant or animal that has become invasive and is harming an ecosystem. I had read about one that is being developed — but not yet approved — to curtail phragmites. Given its prevalence and destructiveness to habitat, a biocontrol for phragmites would be a game changer in the United States.
There is already a viable biocontrol against hemlock woolly adelgid, the insect that has been decimating hemlock trees on the east coast, and the scientist working on this biocontrol is right here in Connecticut.
Carole Cheah is an agricultural scientist with the Connecticut Agricultural Experiment Station and I spoke with her recently.
The woolly adelgid is a small, aphid-like insect that comes from Japan where it feeds on Hemlock and Spruce trees. It was accidentally introduced in Virginia in the 1950’s where it found Hemlock trees here to its liking. The woolly adelgid’s telltale white fluff is easy to spot on hemlock stems. It has been decimating trees for years here, and many have already died.
Dr. Cheah has been studying the issue for over 30 years. After her predecessor at the CAES traveled to Japan and brought back the one insect that only feeds on woolly adelgid, the lady beetle (Sasajiscymnus tsugae), Carole worked to understand the viability of introducing this insect to the U.S.
These lady beetles are black and the size of a sesame seed. Since they only feed on woolly adelgid, the potential of lady beetle damage to other plants and insects was not an issue, as can be the case with introducing biocontrol. The key to this solution’s viability was, then, rearing the lady beetle for mass production. Even though the beetles overwinter in mild winters, they do still need to be produced in labs. Funding was accessed to set up an operation to research and rear the beetles in Connecticut and, when funding ran out, Jayme Cabrera, founder of Tree Savers in Jermyn, Pennsylvania, continued to rear them. Tree Savers now remains the sole production source of these beetles which are sold to the public. They are delivered in the spring and should be released when received. An arborist is not needed for release.
Biocontrol for hemlock woolly adelgid obviates chemical control, especially important as chemicals containing Imidacloprid and Dinotefuran, used by arborists against woolly adelgid, are also harmful to beneficial insects.
Currently,Tree Savers has a waiting list for beetles, but last year Dr. Cheah received extra beetles due to over-production by Tree Savers. She released them in the Northwest Corner, specifically in Mohawk Mountain’s Black Spruce bog, at Dean Ravine in Falls Village, around Furnace Brook and at Gold’s Pines.
My final question to Dr. Cheah was about the purple loosestrife re-appearance. She found my observation interesting. It turns out that Donna Ellis, from University of Connecticut, had led the beetle rearing program for loosestrife biocontrol until the USDA funding ended in 2014. Donna then retired in 2019 and since then, nobody has been working on this invasive plants proliferation.
On a different note, for the second year, The Cornwall Garden Club is hosting a native plant sale where you can add gorgeous native pollinators to your garden at gentle prices. I even grew some from seed! Please join us Saturday, May 24, from 11 a.m. to 1 p.m. on the veranda of The Pink House Restaurant located at 34 Lower River Road in West Cornwall.
Dee Salomon ‘ungardens’ in Litchfield County.
