Heterocampa guttivitta (Walker)
Damage and Hosts
The saddled prominent is an important hardwood defoliator that may cause significant damage to the forest resource. Larvae defoliate hardwood stands through the month of July and into early August. Beech and sugar maple are the preferred hosts, but birches and oaks may also be defoliated. Poplar, red maple and ash are completely avoided by the caterpillars. During the western Maine outbreaks of 1970 and 1971 yellow birch suffered the most damage, especially on recently logged areas. The eastern outbreaks of 1974 to 1976 seem to have caused more severe damage to beech, especially where the beech scale-Nectria complex and drought had previously weakened the trees. Two successive years of severe defoliation may cause some dieback or tree mortality of already weakened trees on poor sites. Heavy defoliation is also believed to be responsible for lowering the sap yield in sugar maple orchards. In resort or recreational areas large numbers of caterpillars and their droppings may be a real nuisance and in some cases may induce a toxic skin reaction if handled in excess.
Outbreaks appear suddenly and do not seem to follow any particular cycle. However, heavy infestations usually subside after one or two years in any one location. Natural control factors such as starvation, disease, parasitism, and predation combine to bring about a sudden collapse of these outbreaks.
Description and Habits
Adults of the saddled prominent are brownish-gray moths, with a wing spread of 1 1/2 to 2 inches. They emerge from early June to mid-July from pupae that passed the winter within the upper 2 inches of the soil and leaf litter.
Eggs are laid individually and mostly on the underside of hardwood leaves from mid-June to mid-July. Hatching takes place after 9-10 days. The majority of the eggs usually have hatched by the middle of July in Maine.
Photo: Maine Forest Service, Forest Health & Monitoring, Photo Collection
Larvae, at first, appear as very tiny reddish-brown "antlered," spiny caterpillars. When the larvae molt for the second stage they lose the "antlers" and are smooth-skinned, except for 2 small horns behind the head. During later stages they lose these horns and are generally of a yellowish-green color. The last stages have a prominent saddle-shaped patch of contrasting red to brown colors on the mid-back. Larvae at this stage resemble those of the variable oakleaf caterpillar but the saddle is much more distinct and mature larvae occur much earlier (July). At maturity, some 5 weeks after hatching when the larvae are about 1 1/2 inches long, they drop or crawl to the ground to pupate.
Stripping of hardwood stands appears to take place suddenly during the latter part of July and in August. However, feeding by the first few stages of the caterpillars usually goes unnoticed. Upon hatching, the tiny larvae are found feeding on the underside of the leaves where they merely skeletonize small patches (windows). The second and third stages then start feeding along the leaf margins and start to consume entire leaves except for the larger veins and stems. As they grow larger, the larvae accelerate their consumption of food with much wasteful feeding, and when present in large numbers cause rapid defoliation.
Bacillus thuringiensis (Bt), carbaryl and cyfluthrin are registered for the control of the saddled prominent.
*NOTE: These recommendations are not a substitute for pesticide labeling. Read the label before applying any pesticide. Pesticide recommendations are contingent on continued EPA and Maine Board of Pesticides Control registration and are subject to change.
Caution : For your own protection and that of the environment, apply the pesticide only in strict accordance with label directions and precautions.
MAINE DEPARTMENT OF AGRICULTURE, CONSERVATION AND FORESTRY
Maine Forest Service - Forest Health and Monitoring Division