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IV. Pest groups

a. Homopteran pests (scales and mealybugs, aphids, whiteflies)

Scales and mealybugs are one of the most destructive groups of insects to ornamental crops.

There are numerous types of scale insects but the three largest groups are the armored scales,

soft scales and mealybugs. The armored scales secrete a waxy covering over their body but is
not attached to their body. The scale insect lives and feeds under the covering. Armored scales

vary in size from 1/16 to 1/8 inch in diameter, can vary in color and in shape. Soft scales also

secrete a waxy covering, but it is part of the insect body. Soft scale vary widely in color, size

and shape and can range from 1/8 to ½ inch in diameter and sometimes may be nearly flat.

Mealybugs are soft-bodied insects that are covered with white, powdery or cottony, wax like

material. Some mealybugs also have waxy projections or filaments extending from their body.

They vary from 1/8 to 1/5 inch in length and tend to congregate together appearing like fluffs

of cotton on the plant. Virtually every woody plant is subject to attack by one or more species

of scales. Some scales attack only a few species while others attack a wide variety of plants.
Scale insects are usually around all year. On many ornamental plants, scales cause plants to

look unhealthy and produce little new growth. Scales feeding on the underside of leaves, may

cause yellow spots on the upper surface and ultimately cause leaf drop. Scales can be found on

all plant parts depending on the type of scale and host plant. Soft scales and mealybugs excrete

large amounts of honeydew which ultimately results in the growth of sooty mold.

Aphids, also called plant lice, are soft bodied, and usually pear-shaped. Their color varies

according to size. The most common ones are green, yellow, or black. The most distinguishing
feature in the identification of aphids is the two short tubes (cornicles) which extend from the

end of the body. Most aphids are wingless, but when colonies become overcrowded or the

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