Also known as genista broom moth, the sophora worm commonly rears its hungry head this time of year. The damage that this critter leaves behind is often noticed before the culprit is caught in action, but you can catch them early and mitigate the damage if you know what to look for.
One of the first signs of sophora worms is the presence of loose webbing around a plant’s new growth at the tips of branches in April and May. Upon closer inspection, you’ll notice that the younger leaves have been chewed in irregular patterns. You may see several smaller caterpillars grouped together within the protective webbing, or a larger caterpillar chewing away by itself.
An older, established plant is not typically harmed by these insects. However, young plants and those that are in poor health or trying to get established in the landscape should be watched closely to catch infestations early. Texas mountain laurel grows quite slowly, and a young or struggling plant doesn’t need the extra setback of having its new growth chewed off. In addition, Texas mountain laurel will only bloom on one-year-old wood, so removal of new growth can affect the plant’s ability to produce next year’s beautiful and fragrant springtime blooms that we’re all so fond of.
The most common complaints against the sophra worm in Tucson comes from gardeners wishing to protect their Texas mountain laurel, but it can be found on many different plants in the legume family (Fabaceae), including acacias and lupines. Thankfully, many of the other host plants grow quickly enough to easily negate the pest’s damage.
If you catch them early, treating these pests can be as easy as pruning out affected areas of the plant or hand-picking individual worms and destroying them. If necessary, larger infestations can safely be treated with Bt worm killer (an organic pesticide), or with a product containing spinosad, like Captain Jack’s Deadbug.