Phantasma Scale Field Detection and Potential Host Plants of Fiorinia phantasma Cockerell & Robinson

Fiorinia phantasma Cockerell & Robinson (Diaspididae: Hemiptera), phantasma scale, is a significant pest of nursery plants, particularly of ornamental palms. The scale has been transported to new localities by movement of live nursery stock (Ahmed and Miller 2018). It was first found in the Philipine Islands in 1915 (Cockerell and Robinson 1915). In the last decade, it had a major global expansion and is now known in 22 countries and territories (American Samoa, France, French Polynesia, Grenada, Guam, Hawaii, Hong Kong, Indonesia, Malaysia, Maldives, Nauru, the Netherlands, New Caledonia, Papua New Guinea, Reunion, Saint Martin, St. Barthelemy, Singapore, Solomon Islands, Taiwan, Thailand, United States and Vietnam) (Ahmed and Miller 2018). The first U.S. continental record (FDACS-DPI sample # E2018-789-1) was collected from Phoenix canariensis Hort, Canary Island date palm on March 1, 2018 from Miami-Dade County, Florida. More samples (FDACS-DPI sample # E2018-1244-1) from the same host plant species in the same area were collected on March 22, 2018. All trees sampled were heavily infested with F. phantasma. Heavy infestations of F. phantasma have also been reported from palms in Hawaii and Grenada (Garcia 2011). The scale has been introduced to new areas without its natural enemies and has the potential to cause serious damage (Garcia 2011; Garcia and Hara 2011; Watson et al. 2015). Its preference for palms may be of concern in Florida where palms are important components of natural and ornamental environments.

There are six species of the genus Fiorinia in the U.S. [F. proboscidaria Green, F. fioriniae (Targioni Tozzetti), F. japonica Kuwana, F. externa Ferris, F. pinicola Maskell and F. theae Green] (See Table 1). All of them require microscopic analysis to be distinguished.

Table 1. Species of the genus Fiorinia reported from the U.S., their geographical distributions and potential occurrences on palms.

The first detection of Fiorinia phantasma in Florida involved more than 20 heavily infested trees along a roadside in Miami-Dade County (Ahmed and Miller 2018). The number of life stages present and density of scales on the trees indicated the population had been there for an extended period. It is not surprising this infestation remained undetected, as the scale is identical in field appearance to other species in the genus Fiorinia that occur in Florida on similar or identical hosts.

Initial scale infestations usually start with the arrival of crawlers (first instar, mobile stage) either blown in the wind, on plant material, or on pruning and gardening tools. Crawlers then settle on plant parts and molt to the second instar within a few days. An initial infestation usually starts within the fold of a leaflet, either near the base or randomly on the upper side of the palm leaves. The first generation commonly stays hidden in the upper leaf fold and is easily missed if only the underside of the palm leaves are inspected. It is necessary to cut leaves and open the upper fold to check for hidden infestations. The second generation may come out of the fold to find new colonizing sites on the lower side of leaves.