University City

Gardening with Don Boekeheide: Watch your step – beetles at work

The cankerworms may not be as bad this spring as in past years, but there are still enough to be plenty annoying, eating holes in leaves, festooning doorways with webs and blanketing walkways and cars with frass.

In our yard in Autumnwood, along Toby Creek near UNC Charlotte, most of our trees and shrubs have done OK. Only the poor apple tree got munched severely (again).

Maybe the late cold snaps and long winter suppressed the 2014 cankerworm outbreak; perhaps tree banding has helped. But there is another ally in the fight against cankerworms you may see right now in your yard or on the sidewalk.

Watch your step! One may go running by, right beside your feet.

They are called Fiery Ground Beetles, also known as Fiery Searchers and Caterpillar Hunter Beetles. These big, active ground beetles, up to 1 1/2 inches long with beautiful iridescent green bodies, are out in force this year, from Pineville to Davidson.

Harmless to humans, they are voracious predators of cankerworms and other soft bodied pests.

“The number of Fiery Ground Beetle specimens submitted to Extension for identification has increased as the number of cankerworms has increased,” said David Goforth, N.C. State University Cooperative Extension Horticulture Extension Agent in Cabarrus County.

“I feel like this is one of the predators that will help control the cankerworms,” Goforth said. “Not sure how well this predator can survive in our urban lawns, but I wish them the best of luck.”

Fiery Ground Beetles (Calosoma scrutator) are found throughout Canada and the United States. They hibernate in the soil and emerge in the spring to start chowing down on cankerworms and other softbodied prey.

The larvae, looking like ominous gray armored grubs with razorsharp jaws, are even more voracious than the flashy adults. They feed mostly at night. Though they are not dangerous to people, keep a respectful distance. Organic Gardening Magazine recommends handling only with gloves on, because of caustic secretions the beetle can release for protection.

Ground beetles have a long history of being recognized as “good bugs” that benefit landscapes, gardens and farms. An 1885 entomology guide from New England “found them on the elm trees in New Haven, Connecticut, eating cankerworms, just below the tin bands with which the trees were protected.”

More recent research supports tradition, finding that ground beetles not only help control insect pests, but they can even put the bite on weed seeds.

Science News ( reports that English and French researchers have confirmed that ground beetles play a role in weed control, especially grassy weeds. With the right management, researchers believe, ground beetles could replace some herbicide applications while significantly reducing weed populations.

One tool to accomplish this is for gardeners and farmers is to leave and preserve areas of undisturbed natural wildlife habitat. The Brits have even come up with a catchy name for this: “beetle banks.”

“By studying whole biological systems, such as farm ecosystems, we can spot the various contributions made by different aspects of a system, including these beetles,” said professor Douglas Kell of the European study. “This project makes the link between biodiversity and food security very clear.”

So, go easy on the pesticides. Even relatively nontoxic sprays that can be used by organic gardeners and farmers often affect beneficial organisms as well as pests. Such key predators as ground beetles are hit especially hard.

And watch your feet. No need to squish ground beetles as they scurry around; in fact, that’s counterproductive. They are the good guys, working on our side.

As ecologist and entomologist E.O. Wilson reminds us:

“ ‘Little things that run the world’ are crucial to the survival of the larger creatures, including ourselves.”