The Asian Cycad Scale Problem

In general, scale insects hatch into a "crawler" stage capable of movement. When they find a suitable spot on a plant, they insert their mouthparts, called a stylet - (much like a straw), into the plant and start feeding. Shortly afterwards they begin to create a covering over themselves. They will stay this way until they die.

Asian Cycad Scale Infestation
Photo by Holly Glen

The unusually dense populations and rapid spread of Asian cycad scale suggests it is an exotic invasive and has few, if any natural enemies. This pest appears to be spread short distances by wind dispersal of crawlers and longer distances by transport of infested plants (Weissling, 1999). If left untreated, this pest will kill its plant host (Howard, 1999).

At its worst, an infestation of the Asian cycad scale can completely coat a medium-sized sago within months and kill it within a year (Howard, 1999). The scale can eventually form several layers and include a high proportion of dead, as well as live scale insects. Heavy infestations can include up to 3000 scales per square inch in several layers (Weissling, 1999).

The Asian cycad scale is unusual in that it can also infest the roots of cycads. These scales have been observed at depths up to 24 inches (Weissling, 1999).


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