IRR2004.03

Invasive Insect Report 2004.03

Cycad scale, Aulacaspis yasumatsui (Homoptera: Diaspididae)

Images

• 
• 

Notes

The cycad scale, Aulacaspis yasumatsui, also known as the sago palm scale or cycad aulacaspis scale, was first detected on Guam in the Tumon hotel district during December 2003. Several sago palms, Cycas revoluta, and endemic cycads (fadang), Cycas micronesica were heavily infested. The scale was identified by Thomas Watanabe of the USDA-APHIS in Honolulu from preserved samples of fronds which were sent to him. These samples also harbored a second scale previosly undetected on Guam,and the false oleander scale, Pseudaulacaspis cockerelli.

Native to Thailand and southern China, the scale is believed to have been accidentally introduced into Florida through the legal importation of cycads (McLaughlin 1998). The scale may also have been introduced into Hawaii from Florida in 1998. It is likely that A. yasumatsui arrived on Guam as a hitch hiker on cycads imported from Hawaii or Florida.

On Guam, the cycad scale has become a major pest, attacking cycads used for landscaping and also the endemic Cycas micronesica which is a major component of Guam's flora. Severe infestations of cycad scale will kill cycads within a year. Insecticidal control may protect landscaping plants, but is probably not an option for protecting wild endemic cycads. In Hawaii, A. yasumatsui populations are controlled to some extent by the ladybeetle, Rhyzobius lophanthae, which was introduced in 1894 for as a biological control agent for other scales insects. There were two unsuccessful attempts to introduce R. lophanthae into the Mariana Islands in 1925 and 1926. Reintroduction of R. lophanthae as a biological control agent for cycad scale on Guam should be considered.