Last May I posted a much-read report of an extreme outbreak of Genista Moth larvae on two treasured Mountain Laurel trees my family had transplanted to our Llano River ranch 10 years ago.
The post, “Squish remorse” — Genista Larvae on Mountain Laurels Create Caterpillar Quandary,” started like this:
“It was an odd day, digging up wild parsley in search of chubby, Eastern Swallowtail caterpillars for fostering and fun at home, followed by hours of trying to figure out a humane and responsible way to kill hundreds–no, thousands–of unwelcome critters decimating several precious Mountain Laurels.”
The Genista Broom moth caterpillar, Uresiphita reversals, occupied almost every leaf of the tree. Sometimes called the Sophora worm, these moth larvae relish the toxic leaves of our native Texas Mountain Laurels, Sophora secundiflora.
A year ago, the voracious caterpillars were decimating the evergreen native, which produces a Kool-Aid perfumed bloom that typically signals the first days of spring.
At the time, I was concerned the ubiquitous caterpillars would kill the tree or prune it to a shadow of its former self. Several sources assured me not to worry—it was all part of the life cycle.
Twelve months later, I’m happy to report that the Mountain Laurels in question have rebounded magnificently. See the photo below.
That’s the good news.
The bad news: the Genistas have moved on to devour another Mountain Laurel further up the hill from their 2013 feast. As Sandra Schwinn commented at the time:
“I have dealt with these for the last couple of years…. If there were just a few of them, it wouldn’t be so bad. Be prepared for a second onslaught, as that’s been my experience. In fact, last year, I battled them from spring into fall.”
Sounds about right. While it’s reassuring that the caterpillar onslaught doesn’t appear to kill the plant, it does rob us of the next year’s purple blooms since Mountain Laurel flowers only occur on second year growth.
Given the apparent heartiness of the Mountain Laurel I will resist the urge to squish the Genistas, letting nature take its course and ceding their role in the food web as fodder for lizards, wasps and others.
- “Squish remorse” — Genista Larvae on Mountain Laurels Create Caterpillar Quandary
- Black Witch Moth: Common, Bat-like and Harmless
- Tomato Hornworm: Loathed by Gardeners, but Morphs into the Magnificent Sphinx Moth
- How do Caterpillars Move? They go with their Gut
- A Year in the Life of a Mostly Native Urban Butterfly Garden
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I have discovered these caterpillars on our Bluebonnet plants. Didn’t realize that ANYthing ate Bluebonnets?
This was so helpful… just found these little guys all over my Mountain Laurels. Can you recommend a quick removal for them ? Sevin dust ?
I discourage pesticides. They don’t hurt the tree—it will bounce back even stronger.
Because these caterpillars ingest and accrete the toxins in Texas Mountain Laurel, rendering them inedible to most predators, they have little “role in the food web as fodder for lizards, wasps and others.” They serve little purpose other than to devour and disfigure my beloved shrubs. On only one occasion I have seen an assassin bug attack one.