Armored Scales
Ivy/Oleander Scale Pseudaletia unipuncta
False Florida Red Scale Chrysomphalus bifasciculatus
Boisduval's Scale Diaspis boisduvalii
Fern Scale Pinnaspis aspidistrae
Purple Scale Lepidosaphes beckii
Description
Armored scales either are oyster-shaped, with arcs of wax being layed down, or circular-shaped with arcs of wax pivoting around a central point or nipple. The Ivy or Oleander Scale is grey or dirty white, circular and flat with a somewhat off-center nipple. The False Florida Red Scale is also circular with a central nipple and is dark red to nearly black. A third circular scale, Boisduval's scale is white and flattened while the male is smaller and elongate with three powdery ridges along the back.
Figure 1. Adult Fern
Scale
Oystershell-shaped scales include the Fern Scale and the Purple Scale. Female Fern Scales are pale brown and males have white upper surfaces, parallel sides, and three longitudinal ridge. Purple Scales are dark brown or purple with the males slightly smaller and narrower than the females and more nearly parallel sided.
Life History
For most armored scales, eggs are laid under the female cover and hatch with young crawlers emerging. The crawlers migrate to suitable feeding sites and then settle down and become sedentary. Upon settling down, the crawler inserts a thread-like mouthpart through the epidermis of the leaf or bark and begins to feed. After feeding for a short time, the crawler molts and sheds its antennae and legs. Female crawlers molt twice prior to becoming an adult. Males have a pupal stage after the second molt and then emerge as yellowish winged insects with two wings, antennae, 3 pairs of legs, and a long appendage extending from the abdomen.
Figure 2. Florida Red
Scale (Adult &
Immatures)
Mating occurs with the male dying shortly afterward. Armored scales may be found on both the leaves and stems of host plants forming thick crusts. They normally are found on the undersides of the foliage, but may be on upper surfaces as well. Under greenhouse conditions, there may be 3 - 6 generations per year.
Scale Species
Ivy or Oleander Scale
False Florida Red Scale
Boisduval's Scale
Fern Scale
Purple Scale
Hosts
Many indoor plants
Palms, Rubber Plants, Figs
Palms, Banana, Cacti, Orchids
Ferns and Aspidistra
Citrus and others
Damage
Armored scales are sap-feeding insects and cause further damage by injecting toxins into the host plant while feeding. Feeding damage may cause yellow or brown areas around the feeding site and eventually leaf death. Unlike soft scales, armored scales do not produce honeydew.
Figure 3.
Scale Crawler
Nonchemical Control
Pruning out heavily infested branches, releasing predators (green lacewing), and parasitic wasps may help reduce scale populations.
Chemical Control
Insecticidal sprays for crawlers may be applied.