After examination by the experts in the department of entomology at the University of Arizona, the culprit has been identified as Antigastra catalaunalis, a moth new to the United States.
As you can see from the photo to the right, the damage to the leaves is severe – they become dry, brown, often rolled at the edges and there is lots of webbing. Click on the photo for better detail.
At this point, no one is really sure how to handle it. The UofA experts suggest that the first frost of winter might knock them out, but in the meantime they are hitting Tecoma plants pretty hard. Amy’s lost about a third of the leaf material on three of her four Tecomas.
Kelly Young, a horticlture agent at the UofA Cooperative Extension here in Maricopa County, suggests a wait and see approach to the pest. If it is necessary to use chemical controls, she recommends a Bt (Bacillus thuringiensis) product. We carry the Hi-Yield brand. Use at the maximum labeled rate. The moth larvae’s habit of covering itself in leaf material means contact insecticides will probably not work.
Let’s hope for a good frost that knocks this out, because Tecomas are a beautiful, hardy addition to landscapes in hot climates like ours.