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Karo felted scale - Eriococcus pallidus

By N A Martin (2018)

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Click to collapse Classification Info






Eriococcus pallidus Maskell, 1885

Click to collapse Common names Info

Karo felted scale, Pallid eriococcus

Click to collapse Synonyms Info

Acanthococcus pallidus (Maskell, 1885)

Nidularia pallidus (Maskell, 1885)

Click to collapse Biostatus and distribution Info

This endemic scale insect lives on leaves and stems of many trees and shrubs. It is mainly found on indigenous (native) plants in native habitats and in parks. It is present in the North and South Islands.

Conservation status: A native species found mainly in native ecosystems on native trees and shrubs in the North & South Islands.

Click to collapse Life stages and annual cycle Info

Karo felted scale breed in spring and summer when there is new growth on host plants. There appears to be at least one generation per year with adult males being produced in spring and early summer. In Auckland, females with eggs and releasing crawlers, first instar (stage) nymphs were found in November. Nymphs and young females were found on young shoots in December and January. There may be a second generation later in the summer.

The tan coloured sacs of the male and females are found on leaves. The female sacs contain the mature mated female who lays eggs in a brood chamber in the sac. After they hatch from eggs, the first instar (stage) nymphs, walk to a young stem where they start to feed. The first instar nymph, often called a crawler, is like all the nymphal stages and the adult females being oval-shaped and having three pairs of legs and a pair of antennae. These stages also have a short rostrum on the underside of the head that holds the stylets used for feeding. The upper side of the body of these feeding stages have short dark setae develop longer white wax spines. When a nymph is fully grown it moults, their skin splits allowing the insect to grow a new and larger skin. There are three female nymphal stages and two male nymphal stages. When an adult female reaches a certain size it walks to a leaf and settles on either the underside or upper side, often near others. On the leaf it makes its felted sac. It is not certain whether it still feeds and if it is mates before or after making its sac.

The fully grown male second instar nymph also walks to a leaf and makes a sac in which it passes through two legless, non-feeding stages, a prepupa and a pupa. The moulted skins are pushed out the open rear end of the sac. The adult male has a pair of wings and while the body is hardening in the sac, it grows a pair of long white wax tails that help balance the male during flight. It walks over leaves and shoots looking for females with which to mate. It may also fly to other shoots and trees to find colonies Karo felted scale. The adult male does not feed.


Adult females and nymphs of Karo felted scale have sucking mouthparts. Specially shaped long rods called stylets are used for feeding. Until used for feeding the tips of the stylets held in the short sheath-like rostrum. When it wishes to feed, the scale insect moves the tip of the rostrum onto the surface of the plant. The stylets are then gradually pushed into the plant. The stylets form two tubes, one down which saliva is pumped into plant cells and the second tube through which it sucks the contents of the plant cells. The insect inserts its stylets into the phloem, the plant vessels for transmitting sap from the leaves to other parts of the plant. The sap has a high volume of water and sugars, more than the insect needs. It excretes the excess water and sugar, which is called honeydew.

Walking, flying and dispersal

The nymphs and adult males and females retain legs and can walk. Fully grown females walk from their feeding site to a leaf on which to form a felted sac. The first instar, which is commonly called a crawler, is the main stage for dispersal. Most crawlers walk to a place on a plant stem where they settle to feed. Some crawlers disperse to other stems and branches. Some to other trees or shrubs; most long distance dispersal is by air. It is not known if crawlers of this species go to high points of the plant and stand up to catch the wind. Adult males have wings as well as legs. They can walk over leaves and stems in search of females with which to mate. They can also fly to nearby colonies, and may be carried further by wind.

Click to collapse Recognition Info

Felted scale insects (Eriococcidae) require specialist skills for their identification. The felted sacs of Karo felted scale are typical of those of many felted scale insects. However, where Karo felted scale is the only species of Eriococcidae that forms sacs on leaves of a plant species, then the Karo scale insects can be recognised and identified. If young stems of a plant with male and female sacs are examined with the aid of a magnifying glass, the feeding nymphs and young females may be seen.

Click to collapse Natural enemies Info

Parasitoids and predators are known, but no pathogens of this scale insect have been reported.


Unnamed parasitic wasps (Hymenoptera) have been reared twice from Karo felted scale.


Four species of ladybirds have been found feeding on Karo felted scale insects. Some feed on the scale insects in their felted sacs, while they all feed on the ‘naked’ insects. The naked insects may be preyed upon by birds and other predatory insects. The two endemic Rhyzobius species have different looking larvae and adults. The adult of Rhyzobius sp. A is black like many named and unnamed Rhyzobius species and is awaiting identification.

Table: Predators of Karo felted scale, Eriococcus pallidus (Hemiptera: Eriococcidae), from Plant-SyNZ database (27 January 2018). The reliability index shows the quality of evidence for the host association (0-10, 10=high quality).
Scientific NameCommon NameClassificationEnemy TypeReliability IndexBiostatus
Cryptolaemus montrouzieri Mulsant, 1853Mealybug ladybird (Beetle)Coleoptera: Coccinellidaepredator10adventive
Rhyzobius acceptus (Broun, 1880)Karo felted scale ladybird (Beetle)Coleoptera: Coccinellidaepredator10endemic
Rhyzobius sp. A of Martin 2017Rhyzobius ladybird (Beetle)Coleoptera: Coccinellidaepredator7endemic
Serangium maculigerum Blackburn, 1892Citrus whitefly ladybird (Beetle)Coleoptera: Coccinellidaepredator9adventive

Click to collapse Host plants Info

Karo felted scale live on the stems and leaves of many trees and shrubs. The feeding stages are found on young stems often at the base of leaves. The mature females and the fully grown second instar males move to leaves on which to settle and form their felted sacs.

There is one record from a fern that needs to be confirmed.

Feeding and honeydew

Like other Hemiptera, Karo felted scale insects have sucking mouth parts. The long stylets, special shaped rods, are held in a short rostrum on the underside of the body. When the insect wishes to feed the stylets are then gradually pushed into the plant. The inner pair of stylets, form two tubes, one through which saliva is injected into the plant and a second through which plants juices are sucked up into the insect. The Karo felted scale inserts its stylets into the phloem, the plant vessels for transmitting sap from the leaves to other parts of the plant. The sap has a high volume of water and sugars, more than the insect needs. It excretes the excess water and sugar, which is called honeydew.

Table: Host plants of the Karo felted scale, Eriococcus pallidus (Hemiptera: Eriococcidae) from Plant-SyNZ database (12 February 2018). The reliability score shows the quality of evidence for the host association (1-10, 10=high).
Common Name(s)Scientific NameFamilyReliability IndexBiostatus
Black tree fern, Black mamaku, Korau, Mamaku, Pitau, KatātāCyathea medullaris (G.Forst.) Sw.Cyatheaceae10indigenous, non-endemic
Wineberry, Mako, MakomakoAristotelia serrata (J.R.Forst. & G.Forst.) W.R.B.OliverElaeocarpaceae10endemic
Marble leaf, Motorbike tree, Kaiwētā, Piripiriwhata, Punawētā, Putaputawētā, PutawētāCarpodetus serratus J.R.Forst. & G.Forst.Rousseaceae10endemic
Tree coprosma, Mamangi, MāmāngiCoprosma arborea KirkRubiaceae10endemic
Thin leaved coprosma, AruheCoprosma areolata CheesemanRubiaceae10endemic
Miki, Mingi, MingimingiCoprosma propinqua A.Cunn. var. propinqua A. Cunn.Rubiaceae8endemic
Glossy karamu, Kākaramū, Kākarangū, Karamū, Kāramuramu, KarangūCoprosma robusta RaoulRubiaceae10endemic
Broom, Atlas broomCytisus sp.Leguminosae7naturalised
Red pine, Amoko, Puaka, RimuDacrydium cupressinum Sol. ex G.Forst.Podocarpaceae10endemic
Sticky hop-bush, ake, Ake rautangi, AkeakeDodonaea viscosa Jacq. subsp. viscosa Jacq.Sapindaceae10indigenous, non-endemic
New Zealand mahogany, Kohe, Kohekohe, Koheriki, Kohepi (flowers), Kohepu (flowers), Māota (flowers)Dysoxylum spectabile (G.Forst.) Hook.f.Meliaceae10endemic
ElaeagnusElaeagnus x reflexa C.Morren & Decne.Elaeagnaceae10naturalised
Hangehange, Hīnau, Pōkākā, WhīnauElaeocarpus dentatus (J.R.Forst. & G.Forst.) VahlElaeocarpaceae10endemic
Mahimahi, Pōkākā, Puka, WhīnauElaeocarpus hookerianus RaoulElaeocarpaceae10endemic
EscalloniaEscallonia sp.Escalloniaceae7unknown
Silk tassel bushGarrya elliptica Douglas ex Lindl.Garryaceae10cultivated
Pigeonwood, Kaiwhir, Kaiwhiria, Kōporokaiwhiri, Pōporokaiwhiri, Pōporokaiwhiria, Porokaiwhiri, Porokaiwhiria, PoroporokaiwhiriaHedycarya arborea J.R.Forst. & G.Forst.Monimiaceae10endemic
New Zealand honeysuckle, RewarewaKnightia excelsa R.Br.Proteaceae10endemic
Dwarf mistletoeKorthalsella lindsayi (Oliv.) Engl.Santalaceae10endemic
Pukatea, PuketeaLaurelia novae-zelandiae A. Cunn.Atherospermataceae10endemic
Mairehau, MāireireLeionema nudum (Hook.) Paul G.WilsonRutaceae10endemic
Mangeao, Mangeo, Tangeao, TangeoLitsea calicaris (Sol. ex A.Cunn.) Benth. & Hook.f. ex KirkLauraceae10endemic
Poataniwha, TātakaMelicope simplex A.Cunn.Rutaceae10endemic
Whiteywood, Hinahina, Inaina, Inihina, Māhoe, Moeahu, KaiwetaMelicytus ramiflorus J.R.Forst. & G.Forst.Violaceae10indigenous, non-endemic
White rata, RātāMetrosideros diffusa (G.Forst.) Sm.Myrtaceae10endemic
Scarlet rata, Vine rata, Aka, Akakura, akatawhitawhi, Akatawhiwhi, Amaru, Kahika, Kāhikahika, Rātā, RātāpikiMetrosideros fulgens Sol. ex Gaertn.Myrtaceae10endemic
Clinging rata, Small white rata, Aka, Akatea, Akatorotoro, Koro, Torotoro, WhakapiopioMetrosideros perforata (J.R.Forst. & G.Forst.) A.Rich.Myrtaceae10endemic
 Myoporum sp.Scrophulariaceae7unknown
Red mapou, Red matipo, Māpau, Māpou, Mataira, Matipou, Takapou, Tāpau, TīpauMyrsine australis (A.Rich.) AllanPrimulaceae10endemic
ToroMyrsine salicina Heward ex Hook.f.Primulaceae10endemic
Cottonwood, TauhinuOzothamnus leptophyllus (G.Forst.) Breitw. & J.M.WardCompositae10endemic
Kaikaro, Karo, KīhihiPittosporum crassifolium Banks & Sol. ex A.Cunn.Pittosporaceae10endemic
Mihimihi, Toro, Toru, TotoToronia toru (A.Cunn.) L.A.S.Johnson & B.G.BriggsProteaceae10endemic

Click to collapse Information sources Info

Hoy JM. 1962. Eriococcidae (Homoptera: Coccoidea) of New Zealand. New Zealand Department of Scientific and Industrial Research Bulletin. 146: 1-219.

Plant-SyNZ: Invertebrate herbivore-host plant association database.

Click to collapse Acknowledgements Info

The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.

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