The tuliptree scale has one generation per year in New England, but may have several in warmer locations. They overwinter as second instar nymphs (immatures) on their host plant’s branches. As the temperature warms in the spring, they break dormancy and actively feed on the host's phloem using piercing-sucking mouthparts. After a few weeks, they mature into adults. Mature female tuliptree scales are 0.24 - 0.47 inches in diameter and hemispherical in shape with a distinctive flange around the edge. They range in color from gray-green to orange-pink with mottled black markings, and are enveloped in a self-produced waxy cover. Adult males emerge in early summer (June) as tiny, winged insects. They mate with the females in late August through September, and then die. During the summer, females continue to mature, feeding on the host and producing large amounts of honeydew (sugary liquid excrement). As eggs develop inside the female, she swells and loses her crimped edge. In late summer, the female gives birth to as many as 3000 live crawlers, the only mobile stage of the female tuliptree scale. After this, the adult female dies and turns brown, but may remain stuck to the host plant. Within three days, a crawler must find a suitable feeding site on the host plant, either by crawling or being shifted to a new host via birds or wind. Once a location is found, the crawler inserts its piercing-sucking mouthpart. Crawlers are dark red and about 0.5 mm long. 2-3 weeks after crawlers emerge, they molt into a 2nd nymphal instar and prepare to overwinter.
Tuliptree scale is a nuisance in two ways: by removing host plant sap and by producing honeydew. Removing sap reduces the tree’s supply of nutrients, causing early leaf drop and branch dieback. In repeated heavy populations, severe branch dieback and even tree death may occur. On a two-year old tree, as few as 38 scales is enough to cause tree mortality (University of Florida). A mature tree with a large tuliptree scale population may also quickly decline. As tuliptree scale feeds, it produces large amounts of honeydew, a sticky sweet substance that is used by sooty mold, ants, bees, and wasps for food. As sooty mold colonizes on honeydew-covered leaves, they turn black. Ants will feed on the honeydew and protect the tuliptree scale from predators in hopes of collecting more, potentially negating the effects of tuliptree scale natural enemies.
The first sign of a tuliptree scale infestation is often the obvious presence of sooty mold. Look for black-stained leaves throughout the summer. Another obvious sign is branches that have a warty or bumpy appearance in late summer. These are the mature female scales. The tuliptree scale may colonize the bottom branches of their host plants first, and subsequently move upward (Robert Childs, Personal Communication). Once found, tuliptree scale may be managed in order to protect tree health. In the winter, when branches are easier to see, scout for small, black overwintering second instar nymphs (immatures).
The tuliptree scale is often misidentified as the larger magnolia scale (Neolecanium cornuparvum). To avoid this, check for these key differences:
Size: Magnolia scale can grow up to ½ inch long. Tuliptree scale typically will not exceed ⅜ inch.
Body: While both insects are soft-bodied scales, adult female magnolia scale are pinkish-orange to brown colored insects, while adult female tuliptree scales range in color from light gray/green to orange/pink mottled with black, and their bodies have a "crimped edging" created by a distinct flange around the margin of its protective waxy cover.
A light infestation of tuliptree scale can be removed by hand. If localized, pruning off affected branches can reduce the tuliptree scale population. Destroy removed infested plant material.
Several natural predators and parasitoids of tuliptree scale exist, including the larva of the pyralid moth, Laetilia coccidivora, ladybird beetles, Hyperaspis proba, Hyperaspis signata, Chilocorus stigma, and Adalia bipunctata, and the parasitoid wasps, Anicetus toumeyella, Metaphycus flavus, Coccophagus flavifrons, and Coccophagus lycimnia. However, these are typically not sufficient to reduce an outbreak population of this scale, especially if ants feeding off the honeydew are protecting the tuliptree scale from predation. In some cases, management of the ants may be necessary in addition to the tuliptree scale itself.
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Azadirachtin (NL)
Buprofezin (NL)
Carbaryl (L)
Clothianidin (NL)
Cyantraniliprole (NL)
Cyfluthrin (NL)
Dinotefuran (NL)
Flonicamid+cyclaniliprole (N)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Imidacloprid (L)
Insecticidal soap (NL)
Lambda-cyhalothrin (L)
Neem oil (NL)
Pyrethrin + sulfur (NL)
Pyriproxyfen (L)
Spinetoram + sulfoxaflor (N)
Different chemical management options are available for tuliptree scale at different times of the year. In early spring, before new growth occurs, overwintering second instar nymphs may be managed with dormant (horticultural) oils applied thoroughly over infested branches when temperatures and weather conditions allow according to label instructions.
Crawlers are the most vulnerable life stage of the tuliptree scale because they haven’t yet developed a waxy cover. Check for the presence of crawlers starting in mid-August. If present, contact insecticides may be applied in these areas at this time. Repeat applications may be needed to cover the entire period of crawler emergence, if allowable on the product label. If beneficial insects (natural enemies) are present in the scale population, summer rate horticultural oils or insecticidal soaps may be used to conserve these non-target organisms while managing the scale. If ants are tending the tuliptree scales, contact insecticides with residual properties may be needed to manage larger tuliptree scale populations (Davidson and Raupp, 2014).
Systemic insecticides may be applied through the soil or the bark of the host plant after bloom to manage the tuliptree scale while reducing risk to pollinator populations.
Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), acetamiprid (injection), azadirachtin (injection, soil drench), clothianidin (soil drench), cyantraniliprole (soil drench, soil injection), dinotefuran (soil drench), imidacloprid (soil drench), and neem oil (soil drench).
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
