The Tecoma Leaf-Tier

Last year was the first year that we saw the Tecoma leaf-tier here in Central Arizona.  It came as quite a shock to us at that time because samples started coming in from all over the county, all at the same time.  Not only that, they were also being seen in Phoenix and Tucson.

We were able to identify the insect and learn about its biology.  We also were able to work out management recommendations.  We wondered if the insect would be able to become established in our climate and decided to take a wait and see approach.  That question has now been answered.  They are still here and doing their thing.  You guessed it.  Samples are coming in as we speak.  If you are growing one of the Tecoma species, let me provide a little background information on this insect pest, what to watch for and what to do if you find the feeding damage.

The insect pest is commonly know as the leaf-tier.  Antigastra catalaunalis is the scientific name.  It is a member of the pyralid family. 

It is important to know that the insect feeds primarily on yellow and orange bells, Genus Tecoma. 
Are you familiar with the tecomas?   “Landscape Plants for Dry Regions,” by Warren Jones and Charles Sacamano, recommends four separate species of Tecoma for our area.  Tecoma alata is commonly known as orange bells or orange-flowered tecoma.  The Argentine tecoma is Tecoma garrocha.  Tecoma stans angustata is the narrow-leaf yellow bells, sometimes called the narrow-leaf trumpet bush; and the fourth is Tecoma stans stans, or the Mexican yellow bells.  All are shrub-like plants.

The tecomas are fairly common in area landscapes.  We like them because they are drought resistant; produce large, showy flowers and, until last year, were pretty much problem free.

The samples are all the same. Instead of a healthy green, many of the leaves are a pale tan where the leaf tissue has been eaten down to a thin, almost transparent layer.  On some plants, the damage can be fairly heavy; in some cases as many as one-half of the leaves showing symptoms.  Some leaves are folded over and sealed with webbing.  No, not spider webs.  The webbing is more dense, like a protective covering that some moth larvae use to protect themselves.  The webbing is speckled with small, black fecal droppings.  In the business, the name we use to describe these droppings is frass. 

The webbing and the frass are a dead giveaway that the insect is a moth and the treatment of first choice for these caterpillars is pretty straight forward.  In almost all cases, we recommend the use of an environmentally safe and organically approved bacteria-based insecticide called Bacillus thuringiensis, or “Bt” for short.

Bt is the active ingredient of a pesticide approved not only by the Environmental Protection Agency but also by organic standards for moth larvae feeding on landscape, ornamental and vegetable plants.  It causes a bacterial disease in the larval stage of the insect’s development.  Once they pick up the disease organism, and it begins to work, the animals stop feeding, get sick and die.  It is generally pretty effective and altogether safe for other animals and plants, including humans.  We use it in many situations and, like I said, it is usually a good choice for moth larvae pests.

If you find symptoms on Tecoma, first determine the amount of damage that you are seeing.  If it is only one or two leaves, you may want to hold off on taking action.  I recommend that you take a "wait and see" attitude. Plants can take a lot of feeding damage without significant harm.  If the symptoms of damage continue to get worse and you need to use a  chemical control, use a Bt subspecies kurstaki product at the maximum labeled rate. The caterpillar's habit of protecting itself with webbing and folded leaves means that contact insecticides, insecticides that you spray onto the insects themselves, will probably not work.

If you have questions, you can reach one of the Master Gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande.  The telephone is (520) 836-5221, extension 204.  The author’s email address is gibsonrd@ag.arizona.edu.

The University of Arizona is an equal opportunity, affirmative action institution.  The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

Rick Gibson
Extension Agent, Agriculture
University of Arizona Cooperative Extension
820 E. Cottonwood Lane, Building C
Casa Grande, Arizona 85122
Voice:    (520) 836-5221
Fax:    (520) 836-1750
email:    gibsonrd@ag.arizona.edu