Greedy scale—Hemiberlesia rapax and latania scale—Hemiberlesia lataniae
These look-alike, armored scale insects (family Diaspididae) can infest numerous plant species. Although sometimes abundant and unsightly, these scales rarely, if ever, cause significant damage to plants; an exception is kiwifruit.
Greedy scale and latania scale can occur on leaves, stems, and fruit of numerous plant species. Mature females and nymphs are circular, convex, and gray, tan, or white. Distinct concentric rings commonly form on the cover as the scales grow. Mature females are 1/25 to 1/12 inch in diameter. In California, male greedy scales are not known and male latania scales are rarely seen; reproduction is mostly or entirely parthenogenetic.
Greedy scale and latania scale cannot be distinguished in the field. Discriminating them requires expert examination of microscopic characters. These species resemble oleander scale, which may be the most common scale in California. However, the cover of greedy and latania scale females is more globular or raised than the flattened cover of oleander scale. The small, raised, somewhat darker area (exuvia, covering of earlier nymphal stage) of greedy and latania scales is to one side of the cover; the exuvia of oleander scale is near its center.
The many hosts of greedy scale include acacia, bay, boxwood, ceanothus, fruit trees, holly, ivy, laurel, magnolia, manzanita, palm, pepper tree, pittosporum, pyracantha, redbud, strawberry tree, and willow. Latania scale has a similarly broad host list but prefers broadleaved evergreens and in California may be more common than greedy scale. See ScaleNet from the U.S. Department of Agriculture for a complete list of the hosts of greedy scale and latania scale and references for more information.
Armored scales develop through three life stages: egg, nymph, and adult. The scales overwinter as mature females, which begin producing crawlers (mobile first instars) in late winter. Female nymphs develop through two, increasingly larger immature stages before maturing into adults. There are two or more generations per year.
These scales suck and feed on fruit, leaves, and stems of numerous plant species. When abundant they give hosts a crusty appearance, reducing plants' aesthetic quality. However, even when abundant they have no apparent adverse effect on plant health, except for kiwifruit.
Several parasitic wasps and predatory insects feed on these scales as listed for greedy scale and latania scale at ScaleNet. Predators include the black lady beetle (Rhyzobius lophanthae) brown lacewings, green lacewings, minute pirate bugs, and twice-stabbed lady beetle. To conserve (preserve) natural enemies and improve biological control, control ants, reduce dustiness (e.g., periodically hose off shrubs), and avoid the use of persistent, broad-spectrum insecticides and miticides. See Protecting Natural Enemies and Pollinators for more information.
Where the presence of these scales is intolerable, horticultural oil provides control if infested foliage and shoots are thoroughly sprayed when crawlers are active in late winter or spring. See the section "Monitoring" in Pest Notes: Scales for how to effectively time applications by monitoring scale crawlers using sticky tape traps.
Adapted from Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide, University of California Statewide Integrated Pest Management Program (UC IPM) and The Scale Insects of California Part 3: The Armored Scales (Homoptera: Diaspididae), California Department of Food and Agriculture.
Nymphs and mature females of greedy scale.
Mature females of latania scale.