Scale of Passiflora

Disease Information

Scale Insects


Armored scales, family Diaspididae, have a flattened, platelike cover that is less than 1/8 inch in diameter. The actual insect body is underneath the cover. The covers often have a differently colored, slight protuberance. Concentric rings form as each nymphal stage (instar) secretes an enlargement to its cover. Armored scales do not excrete honeydew. Damaging species include Florida red scale and Oriental scale.

Soft scales can be smooth, cottony, or waxy and are 1/4 inch long or less. They are usually larger and more rounded and convex than armored scales. Their surface is the actual body wall of the insect and cannot be removed. Soft scales feed in the fluid-conducting phloem tissue of the plant and excrete abundant honeydew, which is sugary water that drips from their bodies. Soft scales include black scale, brown soft scale and mealie bug.

Females of many scale species reproduce without mating (there are no males). At maturity, adult females produce eggs that are usually hidden under her body or cover. Eggs hatch into tiny crawlers (mobile first-instar nymphs), which are yellow to orangish in most species. Crawlers walk over the plant surface, are blown by wind to other plants, or can be inadvertently moved by people or birds. They settle down and begin feeding within a day or two after emergence.


When plants are heavily infested with scales, leaves may look wilted, turn yellow, and drop prematurely. Scales sometimes curl leaves or cause deformed flowers and fruit.


Scales are often controlled by small parasitic wasps and predators including beetles, bugs, lacewings, and mites. Horticultural oils are specially refined petroleum products, often called narrow-range, superior, or supreme oils. Some botanical (plant-derived) oils are also available. Thoroughly spraying plants at the proper time with oil alone usually provides adequate control.



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