Tulip Tree Scale

Appearance

Mature females grow as large as 6-7 mm in diameter. They are oval, convex, and have a distinct flange around the margin of its protective waxy cover. The waxy cover of a mature female varies from light grayish green to pinkish orange mottled with black (Fig. 1). The body fluid of a live female is also pinkish orange. Adult males are small and only have one pair of wings. Adult males may look like tiny wasp parasitoids as they crawl across the surfaces of an infested plant. The crawler stage of this insect is dark red and about 0.5 mm long.

Behavior

Large numbers of these soft scales may give an infested twig a warty appearance. One of the first indications of an infestation of this pest is the abundance of honeydew (sticky, sugar-rich material) secreted by developing soft scales during the growing season. Ant and wasp populations that seek the honeydew are often found in association with this soft scale insect. These ants may need to be managed since they protect this scale insect from predators and parasitoids. The honeydew is a substrate on which black sooty mold grows. The sooty mold may turn the leaves, twigs, and other surfaces beneath an infestation black. Feeding by this pest may weaken young trees by removing plant fluid. In some instances this species may be so prolific that it covers all of the twigs and branches. This could result in a rapid decline of an infested tree.

Predators

There are several natural enemies that attack this pest. One predator of this soft scale is the larval stage of the pyralid moth, Laetilia coccidivora. However, these predators and parasitoids are seldom capable of effectively managing an infestation.

Overwintering second instar nymphs may be managed with a dormant rate application of horticultural oil made according to label directions in early spring before new growth occurs and after the danger of freezing temperatures has passed. Apply registered insecticides according to label directions against the crawler stage from mid-August through mid-September. Repeat applications may be needed. Soil injection or drenching with a registered systemic insecticide labeled for management of this pest may also be applied according to label directions. Early spring application of these registered formulations usually works best against this species when sufficient soil moisture exists. Prior to applying one of these systemic products, applicators may need to irrigate around an infested plant to provide adequate soil moisture.