Eriococcus pallidus Maskell, 1885
Karo felted scale, Pallid eriococcus
Acanthococcus pallidus (Maskell, 1885)
Nidularia pallidus (Maskell, 1885)
Biostatus and distribution
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.
Life stages and annual cycle
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.
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.
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.
|Scientific Name||Common Name||Classification||Enemy Type||Reliability Index||Biostatus|
|Cryptolaemus montrouzieri Mulsant, 1853||Mealybug ladybird (Beetle)||Coleoptera: Coccinellidae||predator||10||adventive|
|Rhyzobius acceptus (Broun, 1880)||Karo felted scale ladybird (Beetle)||Coleoptera: Coccinellidae||predator||10||endemic|
|Rhyzobius sp. A of Martin 2017||Rhyzobius ladybird (Beetle)||Coleoptera: Coccinellidae||predator||7||endemic|
|Serangium maculigerum Blackburn, 1892||Citrus whitefly ladybird (Beetle)||Coleoptera: Coccinellidae||predator||9||adventive|
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.
|Common Name(s)||Scientific Name||Family||Reliability Index||Biostatus|
|Black tree fern, Black mamaku, Korau, Mamaku, Pitau, Katātā||Cyathea medullaris (G.Forst.) Sw.||Cyatheaceae||10||indigenous, non-endemic|
|Wineberry, Mako, Makomako||Aristotelia serrata (J.R.Forst. & G.Forst.) W.R.B.Oliver||Elaeocarpaceae||10||endemic|
|Marble leaf, Motorbike tree, Kaiwētā, Piripiriwhata, Punawētā, Putaputawētā, Putawētā||Carpodetus serratus J.R.Forst. & G.Forst.||Rousseaceae||10||endemic|
|Tree coprosma, Mamangi, Māmāngi||Coprosma arborea Kirk||Rubiaceae||10||endemic|
|Thin leaved coprosma, Aruhe||Coprosma areolata Cheeseman||Rubiaceae||10||endemic|
|Miki, Mingi, Mingimingi||Coprosma propinqua A.Cunn. var. propinqua A. Cunn.||Rubiaceae||8||endemic|
|Glossy karamu, Kākaramū, Kākarangū, Karamū, Kāramuramu, Karangū||Coprosma robusta Raoul||Rubiaceae||10||endemic|
|Broom, Atlas broom||Cytisus sp.||Leguminosae||7||naturalised|
|Red pine, Amoko, Puaka, Rimu||Dacrydium cupressinum Sol. ex G.Forst.||Podocarpaceae||10||endemic|
|Sticky hop-bush, ake, Ake rautangi, Akeake||Dodonaea viscosa Jacq. subsp. viscosa Jacq.||Sapindaceae||10||indigenous, non-endemic|
|New Zealand mahogany, Kohe, Kohekohe, Koheriki, Kohepi (flowers), Kohepu (flowers), Māota (flowers)||Dysoxylum spectabile (G.Forst.) Hook.f.||Meliaceae||10||endemic|
|Elaeagnus||Elaeagnus x reflexa C.Morren & Decne.||Elaeagnaceae||10||naturalised|
|Hangehange, Hīnau, Pōkākā, Whīnau||Elaeocarpus dentatus (J.R.Forst. & G.Forst.) Vahl||Elaeocarpaceae||10||endemic|
|Mahimahi, Pōkākā, Puka, Whīnau||Elaeocarpus hookerianus Raoul||Elaeocarpaceae||10||endemic|
|Silk tassel bush||Garrya elliptica Douglas ex Lindl.||Garryaceae||10||cultivated|
|Pigeonwood, Kaiwhir, Kaiwhiria, Kōporokaiwhiri, Pōporokaiwhiri, Pōporokaiwhiria, Porokaiwhiri, Porokaiwhiria, Poroporokaiwhiria||Hedycarya arborea J.R.Forst. & G.Forst.||Monimiaceae||10||endemic|
|New Zealand honeysuckle, Rewarewa||Knightia excelsa R.Br.||Proteaceae||10||endemic|
|Dwarf mistletoe||Korthalsella lindsayi (Oliv.) Engl.||Santalaceae||10||endemic|
|Pukatea, Puketea||Laurelia novae-zelandiae A. Cunn.||Atherospermataceae||10||endemic|
|Mairehau, Māireire||Leionema nudum (Hook.) Paul G.Wilson||Rutaceae||10||endemic|
|Mangeao, Mangeo, Tangeao, Tangeo||Litsea calicaris (Sol. ex A.Cunn.) Benth. & Hook.f. ex Kirk||Lauraceae||10||endemic|
|Poataniwha, Tātaka||Melicope simplex A.Cunn.||Rutaceae||10||endemic|
|Whiteywood, Hinahina, Inaina, Inihina, Māhoe, Moeahu, Kaiweta||Melicytus ramiflorus J.R.Forst. & G.Forst.||Violaceae||10||indigenous, non-endemic|
|White rata, Rātā||Metrosideros diffusa (G.Forst.) Sm.||Myrtaceae||10||endemic|
|Scarlet rata, Vine rata, Aka, Akakura, akatawhitawhi, Akatawhiwhi, Amaru, Kahika, Kāhikahika, Rātā, Rātāpiki||Metrosideros fulgens Sol. ex Gaertn.||Myrtaceae||10||endemic|
|Clinging rata, Small white rata, Aka, Akatea, Akatorotoro, Koro, Torotoro, Whakapiopio||Metrosideros perforata (J.R.Forst. & G.Forst.) A.Rich.||Myrtaceae||10||endemic|
|Red mapou, Red matipo, Māpau, Māpou, Mataira, Matipou, Takapou, Tāpau, Tīpau||Myrsine australis (A.Rich.) Allan||Primulaceae||10||endemic|
|Toro||Myrsine salicina Heward ex Hook.f.||Primulaceae||10||endemic|
|Cottonwood, Tauhinu||Ozothamnus leptophyllus (G.Forst.) Breitw. & J.M.Ward||Compositae||10||endemic|
|Kaikaro, Karo, Kīhihi||Pittosporum crassifolium Banks & Sol. ex A.Cunn.||Pittosporaceae||10||endemic|
|Mihimihi, Toro, Toru, Toto||Toronia toru (A.Cunn.) L.A.S.Johnson & B.G.Briggs||Proteaceae||10||endemic|
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. plant-synz.landcareresearch.co.nz/
The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.