Pulvinaria innumerabilis

Distinguished from other Pulvinaria species by the combination of: host association with maples, particularly silver maple; the timing of ovisac production in early summer; and the distinctive fluffy, popcorn-like appearance of the ovisac. Separated from the cottony camellia scale (Pulvinaria floccifera) by host preference—P. floccifera occurs primarily on camellia, holly, and yew, while P. innumerabilis strongly prefers maples. The ovisac of P. innumerabilis is generally more elongated and less dense than that of P. floccifera. Separated from the cottony taxus scale (P. floccifera, synonym) by the same host-based distinction. Separated from other maple-feeding scales by the cottony ovisac; maple leaf scale (Phenacoccus acericola) produces no such structure, and oystershell scales (Lepidosaphes spp.) have elongate, armored coverings.

Associated with the woody stems and leaf undersides of deciduous trees and shrubs. Most commonly found on maple species in urban, suburban, and natural forest settings. Occurs in temperate regions with established host tree populations.

Native to and widespread in eastern North America. Range extends across the United States and southern Canada where host maples occur. Introduced populations have been documented in Europe and other regions outside native range.

Eggs hatch in late spring to early summer (June-July in temperate North America). First instar crawlers disperse to leaves. Nymphs feed through summer, fall, and winter, molting several times. Development completes the following spring. Adult males emerge and mate in spring; females produce ovisacs shortly after mating. Single generation per year (univoltine).

Phloem-feeding sap-sucker. Inserts stylets into vascular tissue of host plants to extract nutrient-rich fluids. Has been documented feeding on Acer spp. (maples, especially silver maple), Robinia spp. (locust), Fraxinus americana (white ash), Euonymus alatus (burning-bush), Quercus spp. (oak), Acer negundo (boxelder), Cornus spp. (dogwood), Celtis spp. (hackberry), Platanus spp. (sycamore), Fagus spp. (beech), Ulmus spp. (elm), Salix spp. (willow), Tilia americana (basswood), and Populus spp. (poplar).

• Acer saccharinum - primary hostStrongly preferred
• Acer spp. - hostAll maple species
• Robinia pseudoacacia - hostBlack locust
• Robinia neomexicana - hostHoney locust
• Fraxinus americana - hostWhite ash
• Euonymus alatus - hostBurning-bush
• Quercus spp. - hostOak species
• Acer negundo - hostBoxelder
• Cornus spp. - hostDogwood species
• Celtis spp. - hostHackberry species
• Platanus spp. - hostSycamore species
• Fagus spp. - hostBeech species
• Ulmus spp. - hostElm species
• Salix spp. - hostWillow species
• Tilia americana - hostBasswood
• Populus spp. - hostPoplar species

Hemimetabolous development with three life stages: egg, nymph, and adult. Females deposit 1,000–1,500 eggs in a cottony ovisac in early summer. Eggs hatch into mobile first-instar crawlers that disperse to leaf undersides. Crawlers settle and insert mouthparts, becoming sessile for remaining nymphal instars. Nymphs overwinter on branches or leaf undersides. In spring, nymphs complete development to adults. Males develop wings and fly to locate females. After mating, females produce ovisacs and begin egg-laying. Single generation per year.

First-instar nymphs are the only mobile life stage, dispersing actively before settling permanently. Adults are sessile; females remain fixed to plant tissue for life once mated. Produces copious honeydew during feeding, which drips onto surfaces below. Does not display maternal care beyond ovisac construction. No known social behavior or aggregation pheromone use documented.

Herbivore that functions as a plant parasite, extracting phloem sap and reducing host plant resources. Honeydew production supports sooty mold fungi (Capnodium spp.) that grow on leaf surfaces, potentially reducing photosynthesis. Serves as prey for various natural enemies including lady beetles (Coccinellidae), lacewings (Chrysopidae), and parasitoid wasps (Encyrtidae). Specific parasitoid associations documented: Metaphycus pulvinariae Howard and Cheiloneurus pulvinariae Dozier have been reared from this species.

Considered a minor pest of ornamental and shade trees. Heavy infestations cause aesthetic concern due to conspicuous white ovisacs and associated sooty mold. Rarely causes significant economic damage; established trees tolerate infestations without long-term harm. Heavy infestations may cause premature leaf drop, twig dieback, and yellowing foliage. Occasionally managed in urban forestry and horticultural settings through horticultural oils, insecticidal soaps, or biological control agents. Not known to transmit plant pathogens. No direct human health significance.

• Pulvinaria flocciferaProduces similar cottony ovisacs, but occurs primarily on camellia, holly, and yew rather than maple; ovisac typically denser and more globular
• Pulvinaria vitisClosely related congener with overlapping morphology; distinguished by host preferences and subtle differences in ovisac structure
• Phenacoccus acericolaAlso feeds on maples but lacks cottony ovisac; produces powdery wax coating instead
• Lepidosaphes ulmiOystershell scale has elongate, armored covering rather than soft body with cottony ovisac

Often mistaken for a serious tree-killing pest due to the conspicuous appearance of heavy infestations. The common name 'cottony maple scale' sometimes leads to confusion with cottony cushion scale (Icerya purchasi), a dramatically different insect in family Monophlebidae that is a serious citrus pest. The white ovisacs are sometimes mistaken for fungal growth or pesticide residue by observers unfamiliar with scale insects.

• soft scale
• maple pest
• ornamental pest
• phloem feeder
• honeydew producer
• univoltine
• temperate
• North American native

• BugGuide
• Wikipedia
• iNaturalist taxon
• Catalogue of Life
• Encyrtid Holdings | Entomology Research Museum
• Flocked hollies - Cottony camellia scale, Pulvinaria floccifera — Bug of the Week