Survival of the cycad aulacaspis scale in Northern Florida during sub-freezing weather

Edwin R. Duke, Alfredo B. Lorenzo, Forest W. Howard


The cycad aulacaspis scale insect, Aulacaspis yasumatsui, was accidentally introduced into southern Florida in 1996. Since its initial discovery in the Miami area, it has been noted in numerous locations throughout the state. In addition, infested plants have been reported in Alabama, California, Georgia, Hawaii, Louisiana, South Carolina and Texas. The primary method of long-distance spread is presumed to be by the transport of infested plants. While the worst infestations tend to be in warmer climates (primarily USDA zones 9 and 10), the presence of the scale in areas where temperatures regularly fall below the freezing point would seem to indicate that the Cycad Aulacaspis Scale can survive in any area where a host plant may be found. In 2001, specimens of Aulacaspis yasumatsui were identified on Cycas revolute plants growing in Leon County (USDA zone 8b). The infestations were purposely left uncontrolled in order to observe the effects of freezing temperatures on scale survival. In February 2002 and again in January 2003, nighttime temperatures in Leon County dropped below 20 F (-6.7 C) for a minimum of 4 h. Live scale insects were found on leaf samples collected within 24 h of each occurrence of freezing temperatures. The new flush of growth occurring on infested plants in the spring 2002 growing season was quickly covered with a white crust of primarily male insects, typical of Cycad Aulacaspis Scale infestations. This seemed to indicate that the insects were not significantly impacted by the sub-freezing temperatures experienced the preceding winter.


aulacaspis yasumatsui; cycas revoluta

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283