My AirPods were blasting Depeche Mode on a recent morning run with my two dogs when all of a sudden I had a faceful of fine, silky thread. I hadn’t even noticed that my neighbor’s tree had seemingly transformed overnight from a healthy hackberry into something you might see in the Addams family’s yard.
The tree’s canopy was covered in so much web it looked like it could be Spiderman’s practice range, with several strings reaching toward the ground, some of which still sported the caterpillar responsible for the infestation.
Though infestations of fall webworms are nothing new, one so widespread is leaving homeowners scratching their heads and pulling web off their homes, cars, and faces.
Fall Webworms
There are two types of caterpillars responsible for webs in trees. Hyphantria cunea is your typical fall webworm.
According to Neil Sperry, a North Texas garden expert, there are usually at least two generations per year, one in the spring and one about now. For this particular worm, not much can be done for the pecans, walnuts, persimmons, and many other Texas trees they attack.
“I have been volunteering at the Dallas Arboretum for over 15 years, and I can recall maybe 10 years ago when there was another webworm outbreak, they had ‘cherry picker’ trucks with buckets that were raised so the infected pecan tree limbs could be cut off,” said Rick Williams, who operates the Dallas Master Gardener help desk. “Just another indication that insecticides don’t work, so mechanical removal was used. I used to have a Mulberry tree in my backyard, and web worms seem to enjoy those leaves as well.”
Normally, these particular worms don’t do a whole lot of damage. As Sperry says, the webworms are infesting trees in the fall, which is after the tree has finished most of its growth cycle. However, they’re hideous, creating bags of worms from which the caterpillars eventually drop. Once the fall webworms have had their fill, they come out of their metamorphosis when they transform into a lovely white, fuzzy moth.
“It’s actually a lovely little creature,” Sperry notes, “but as with humans, its kids make quite a mess.”
The Other Fall Webworm
However, this fall we’re getting a double dose of sticky string in trees with a different species of webworm.
This particular defoliating caterpillar is somewhat of a mystery, attacking hackberry trees all across Dallas-Fort Worth.
“I was not familiar with the hackberry tree caterpillar until multiple questions came into the [Dallas County Master Gardeners] Help Desk recently,” Williams said. “Some research shows that in 2015, the exact ID was a challenge even for experts.”
The perpetrator of these messy webbed canopies was thought to be Sciota celtidella, which is known to attack hackberry trees and has been spotted in the Grapevine and Flower Mound areas of Tarrant and Denton counties. However, when the adults emerged, they were found to be a mixture of webworm species — Sciota rubrisparsella and a moth of the Pococera genus.
That said, there are ways to help support your hackberry or sugarberry trees should they be infested and quickly defoliated by these webworms:
– Supplemental deep watering around the base of trees can help a tree through late summer stress if your soil is very dry
– Most shade trees do not need special fertilization, however you can apply compost and mulch around the base of the tree to help in foot feeding
– For trees in lawns with compacted soil, aeration of the lawn can help the tree better absorb water and nutrients
The City of EulessThe upside to this fall’s massive webworm infestations?
Halloween decorating just got a lot easier.
