Eriococcus

felt scales, bark scales

Eriococcus is a of felt scales (bark scales) in the Eriococcidae, order Hemiptera. These insects are characterized by producing white, felt-like waxy coverings over their bodies. Some , such as Eriococcus lagerstroemiae (crapemyrtle bark scale), are significant pests of ornamental plants, while others like E. spurius damage American elm trees. The of Eriococcidae remains debated, with some authorities placing these species in Acanthococcidae.

Pronunciation

How to pronounce Eriococcus: //ˌɛɹiˈɒkəs//

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Identification

Distinguished from armored scales (Diaspididae) by lacking a hard, separable protective cover; distinguished from soft scales (Coccidae) by the extensive woolly or felt-like wax production rather than a smooth or slightly convex body. Presence of white, cottony or felt-like masses on bark and branches is diagnostic. Must be separated from mealybugs (Pseudococcidae) which have more segmented bodies and often longer waxy filaments. Specific identification requires microscopic examination of morphological features.

Habitat

Bark and branches of woody plants; primarily found on trees and shrubs. Urban and suburban landscapes, nurseries, and natural forests depending on host distribution.

Distribution

distribution with native to various regions; several species are . Documented in North America (United States, Canada), Australia, New Zealand, South Africa, and other regions. Specific distributions vary by species: E. lagerstroemiae invasive in southeastern United States (Texas, Alabama, Georgia, Virginia, Maryland, DC), E. spurius established in western North America (Calgary, Alberta, Canada), E. ironsidei in Australia, Hawaii, and South Africa.

Diet

Phloem-feeding; inserts into plant vascular tissue to extract sap. Heavy feeding depletes plant resources and produces copious honeydew .

Host Associations

Lagerstroemia spp. - primary Crapemyrtle bark scale (E. lagerstroemiae)
Ulmus americana - American elm; E. spurius
Macadamia integrifolia - E. ironsidei
Macadamia tetraphylla - E. ironsidei
Korthalsella spp. - Pygmy mistletoes; E. korthalsellae in New Zealand

Life Cycle

Females lay 100-300+ pink within white felt-like ovisacs. Eggs hatch into mobile first-instar nymphs called that disperse to new locations on the plant or to other plants. After settling, nymphs through subsequent instars, with females remaining and producing waxy coverings. Males typically develop through fewer instars and emerge as winged . Multiple per year occur in warm climates (up to four generations annually); fewer in temperate regions.

Behavior

exhibit active , to new feeding sites. Some demonstrate 'takeoff' behavior to become airborne and ride wind currents to new . Phoretic dispersal on birds, mammals, and other insects has been documented in related scale insects. Females remain permanently attached to host bark after settling, feeding continuously and producing waxy ovisacs.

Ecological Role

Herbivore and plant pest; heavy cause branch dieback and tree death. Honeydew production supports growth, reducing and aesthetic value. Honeydew attracts stinging insects (, bees) and other opportunistic feeders. Serves as for wasps (e.g., Coccophagus gossypariae) and including lady beetles and lacewings, contributing to potential.

Human Relevance

Significant pest of ornamental landscape plants, particularly crapemyrtles in the United States. Economic impact includes plant damage, reduced aesthetic value, costs of applications, and professional arborist services. require management through combining agents, , and insecticides. International trade in nursery stock facilitates spread to new regions.

Similar Taxa

AcanthococcusTaxonomic synonymy; Eriococcus lagerstroemiae sometimes placed in Acanthococcus, reflecting ongoing debate in Eriococcidae
Pseudococcidae (mealybugs)Similar woolly appearance, but mealybugs have more distinctly segmented bodies, longer lateral waxy filaments, and often occur on leaves as well as stems
Diaspididae (armored scales)Both are scale insects, but armored scales produce a hard, separable protective cover (test) rather than soft felt-like wax
Coccidae (soft scales)Both produce honeydew and lack hard covers, but soft scales have smooth, convex, often shiny bodies without extensive woolly wax

More Details

Taxonomic Uncertainty

The classification of Eriococcidae versus Acanthococcidae remains unresolved, with authorities treating these as separate or . This affects generic placement of some .

Invasive Spread Mechanisms

Multiple facilitate range expansion: infested nursery stock trade, phoretic transport on animals, wind-borne with 'takeoff' , and natural spread by crawling nymphs.