Interior Landscapes - Scale and Mealybugs
Description
Scale identity has a large impact on biological control success.
Scales are sucking insects about 1/16 to 1/4 inch in diameter. They are
covered with a tan or brown scale that protects the soft underparts, and
may look like plant bumps. Scales suck plant juices and are classified
as soft or armored. Both have hard shells, but the shell may be removed
from armored scales by lifting with a sharp knife. Only soft
scales and mealybugs secrete a sweet, sticky honeydew which may drop
onto lower leaves or floors and support the growth of a black, powdery
fungus called sooty mold.. Soft scales usually have one generation per
year; armored scales, several. The females are the immobile lumps. Under
the scales, each may hatch up to 1000 eggs at a time. When eggs hatch,
the first larval stage is mobile and known as “crawlers”.
Know your mealybugs!! Mealybugs are small, sucking insects with a
white, waxy covering that gives them a woolly appearance. One species,
the citrus mealybug, Planococcus citri, is oval and pink, with short filaments of wax radiating from the body. Citrus mealybug eggs are laid in cottony appearing groups. The other common mealybug species, the
longtailed mealybug, (Pseudococcus longispinus) has long ‘tail’ filaments which may stick up like little spikes from each cottony mass
of long-tailed mealybugs. Longtailed mealybugs lay live young, not eggs.
Identifying
There are many species of scale. IPM Labs offers a scale identification service.
Crop Management
Avoid over-fertilizing with nitrogen, and control ants that may protect aphids from predators.
Early Detection
Control mealybugs and scales first by limiting new introductions on new
plants brought into the interiorscape. Inspect new plants carefully and
control the pests before installation. Monitoring every other week
for scales and mealybugs will give you a better probability of early
detection and more effective biological control. Examine leaves, stems
and leaf axils and plan for action on first detection.
Physical or Chemical Controls
Reduce scale and mealybug populations directly by pruning infested plant
parts and carefully removing them so that pests do not accidentally
transfer onto clean areas of the plant.
Syringing — knocking mealybugs off plants with a water spray
— is a time-honored method of mealybug control.
Insecticidal soaps, horticultural oils (when not phytotoxic), and
insect growth regulators can be effective. Avoid using most residual
insecticides for a period of three months prior to planned use of
biological controls.
|
