Fall webworm (Hyphantria cunea) moths are flying. I had several reports inquiring about the little white moths around night lights in the last few days in the last week of March.
These are the early generations of the fall webworm. Snowbirds may be familiar with the caterpillar, which webs the ends of various trees' branches (persimmon, mulberry, black walnut, sweetgum and about 100 other species) together late in the summer. Despite the seasonal connotation of its name, this caterpillar has several generations per year, starting in the spring. The later generations are typically more noticeable, with the extensive webbing at the ends of bald cypress tree branches in late September 2003.
As with many insect pests, they are more abundant some years than others. In 2003, I had to look up the hosts to be sure that it attacked bald cypress. Indeed, bald cypress is a favorite, along with south Florida trees such as water hickory and Carolina willow. Larvae in our area are pale-yellow or greenish with two rows of black spots along their "back." They have scattered long hairs and black head capsules.
After feeding, the caterpillar hides in bark crevices and other protected areas on the ground and changes into an amber-brown pupa inside a loose cocoon. The adult is a white moth (some have some black freckles) about 1 inch long which deposits about 200 to 300 greenish eggs in one mass on the underside of leaves.
What to do: The damage caused by this species is considered aesthetic. Typically it is late in the season when the webbing is noticed and the bald cypress would be defoliating soon anyway, so spraying won't protect the trees. Also, with bald cypress, which typically grows along ponds and waterways, the drift from spraying with some insecticides could endanger aquatic life. That means dead fish and frogs, etc. So, it is better to let nature take its course and do nothing.
You should mark your calendar or tickler file to look for the webbing in July and early September and prune out the little web-makers before they become so obvious. If necessary, use a product specific for caterpillars, such as a B.t. (Bacillus thuringiensis) containing product or Ferti-lome's Borer, Bagworm, Leafminer & Tent Caterpillar Spray. Both products would have little impact on aquatic life.
For more information on home gardening, contact the Collier County Extension Service, Master Gardener Plant Clinic, at 353-2872. The downtown clinic is at the Central Avenue Library and is open Thursday, 9 a.m. to noon; call 262-4130. For more information, visit: collier.ifas.ufl.edu
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