If your backyard tree has suddenly and completely lost its leaves, there's a tiny green worm you can blame. It's called the cankerworm, AKA inchworm, and it has invaded trees across Dallas-Fort Worth.
These tiny caterpillars feed off trees, completely defoliating the canopy — specifically the hackberry tree, their favorite. And in fall 2022, they've arrived in North Texas with a vengeance.
Residents from Mesquite on the east to West Fort Worth on the west have spotted the bright green worms, less than an inch long, swaying from silken strings, hanging from door eaves, yard furniture, open porches, anyplace they can catch a breeze.
These cankerworms are a regular part of Texas' fauna, but DFW is experiencing a rare widespread outbreak, says Amy Heath, a Board Certified Master Arborist and the owner of
Texas Tree Surgeons, a tree trimming company based in Garland.
Heath says that her staff of arborists has been seeing the little critters — which she identifies as the sciota celtidella moth also known as the hackberry leafroller — all over North Texas.
"We've just started getting calls because the defoliation has become so dramatic over the last week," Heath says. "People become concerned when they see their trees losing all of their leaves."
While it's weird to see hackberry trees basically stripped of their leaves, it's not a real issue to the health of the tree — it's more of a nuisance, she says.
"You'll find clusters when you go outside, they're dropping out of trees, and the silken string is a little like a spider web," she says.
If they're in your doorway, prepare yourself because once you're inside, you'll probably find one or two in your hair.
Cankerworm outbreaks only come every few years, says Wizzie Brown, an Extension Program Specialist with Texas A&M AgriLife Extension Service.
"They don't follow a calendar year," she says. "Outbreaks usually occur every 3-5 years and it’s not widespread — it's usually in geographic pockets. We had one in Central Texas last year."
Their occurrence is based on environmental conditions.
"Is the temperature right? Is there moisture? Even the daylight cycle," Brown says.
The weird 2022 summer in North Texas — where there was no rain for 100 days, then massive flooding storms — looms as a significant factor.
"That rain prompted vegetation to come out, with new growth," Brown says. "Insects are going to say, 'There’s food available, we need to get cranking'."
The last outbreak that hit DFW was
in 2015, Heath says. This 2022 outbreak began surfacing the week of August 15, and their lifespan is about 4-6 weeks, so they're in their very final days, and their exit is hastened by the cooler nights we're finally starting to see.
"The bigger problem is the underlying stresses we have on our trees right now," Heath says. "This year has been hard on trees. We had the huge freeze in 2021, then this summer of drought, with higher temperatures that came early so the ground around the roots was hotter than it usually is."
"Hackberries get get a root fungus when they get stressed which makes them a risk for total failure," she says. "Most people look at the canopy, but the arborist looks at the bottom of the tree first."
Spraying pesticide isn't considered effective since the inchworms are so widespread and floaty in the air that they're impossible to capture.
"Maybe just get out the water hose and spray your doorway," Brown says.