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.
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.
Figure 1. Adult Fern Scale
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)
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.
Ivy or Oleander Scale
False Florida Red Scale
Many indoor plants
Palms, Rubber Plants, Figs
Palms, Banana, Cacti, Orchids
Ferns and Aspidistra
Citrus and others
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.
Pruning out heavily infested branches, releasing predators
(green lacewing), and parasitic wasps may help reduce scale
Insecticidal sprays for crawlers may be applied.
3. Scale Crawler