Genus Cerataphis [Family Aphididae]
The only aphids that are known to commonly occur on palms are the palm aphids (Cerataphis spp.), which do not look like a "typical" aphid but look rather more like a scale insect. Adult palm aphids are 1-2 mm long, oval and slightly convex in shape, shiny dark brown or blackish in color with a white, waxy, threadlike fringe. Adults are wingless and have short legs that are hidden under the body. They are capable of moving, but they are mostly sedentary. The three immature instars are smaller and light green to olive in color with more noticeable legs.
While aphids in general are typically temperate species, Cerataphis spp. appear to be primarily restricted to more tropical habitats, in correspondence with their host species. They are common on palms throughout the humid tropical regions of the world but are native to Asia. The genus includes from 3 to 10 species, depending on the source.
In their native habitat, aphids of the genus Cerataphis are polymorphic and alternate between two host species, a dicotyledonous primary host and monocotyledonous alternate hosts. The aphids form galls on the dicot host, within which 3 generations are produced: 1) apterous adults, 2) sterile second-instar larvae that act as soldiers, and 3) alate adults which migrate to establish colonies on palms. Aphids are able to survive and reproduce on the monocot host alone in the absence of the natural dicot host. Aphid reproduction on the monocot host usually involves parthenogenesis, live birth, and 'telescoping of generations,' where a female has parthenogenetically produced daughters and granddaughters developing inside her. When necessary due to changes in available resources, winged individuals will be produced that can fly to a new host plant to establish a new colony. When the dicot host is available, male and female aphids will be produced, mate, lay eggs, and form a new gall. In areas where the dicot host is absent, Cerataphis sp. live entirely on the monocot host, the alate forms are rarely seen, and they reproduce asexually. Aphids are capable of having many generations per year due to their prolific reproductive strategy.
Palms: includes coconut palm (Cocos nucifera) as well as other palm species; in Florida, infestations seem to be more common on exotic ornamental palms than on native palm species
Other: primary host is dicotyledonous Styrax sp. in its native region in tropical Asia; other monocotyledonous hosts include bamboos, Pandanus spp., and orchids
Cerataphis brasiliensis and Cerataphis lataniae are the two species of palm aphids. Some taxonomists question whether these are distinct species or in fact a single species.
Cerataphis spp. generally occur in dense aggregations, typically on the young and unopened fronds, but also occasionally on the flowers and young fruits. They produce honeydew, which supports the growth of sooty mold, and they are often tended by ants. Cerataphis spp. are virtually indistinguishable other than by microscopic examination of a slide-mounted individual; confirmation of identification should be done by an expert.
Cerataphis spp. are often confused with whitefly pupae.