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Ctenochiton paraviridis Henderson & Hodgson

Spotted sixpenny scale
[Ctenochiton paraviridis]. L: a young adult female. R: a mature female with several new crawlers nearby on the leaf.

[Ctenochiton paraviridis]. L: a young adult female. R: a mature female with several new crawlers nearby on the leaf.

The species name para = near, with viridis = green, means near to the original sixpenny scale Ctenochiton viridis described by William Maskell in 1879.

This scale is closely related to the three other species of Ctenochiton, the sixpenny scales.

Biology: Has one generation per year and overwinters as small 2nd-instar females and males. As soon as spring growth starts on the host trees, the female scales move off the old leaves onto the new shoots and take advantage of the rising sap to speed up their development to adult. The males stop feeding and stay behind on old leaves; they lose their mouthparts as they moult and go through a metamorphosis to emerge as tiny winged insects quite unlike the female scales. The adult males live for only a few days, long enough to mate with females.

Spotted sixpenny scale is susceptible to attack by 3 fungal pathogens and several hymenopterous parasitoids.

Leaf deformation or "bumps"

This very distinctive effect is caused by female spotted sixpeny scales, and is especially seen on leaves of pigeonwood, Hedycarya arborea.

In the photo, the right-hand leaf has "bumps" on the upper surface. These are caused by the female scales [in the left-hand leaf], which form depressions or hollows on the undersurface. The leaf is permanently deformed and these "bumps" and hollows remain after the scales have died and fallen off.

Found on the undersides of leaves of:

Alepis flavida yellow mistletoe
Corynocarpus laevigatus karaka
Dodonaea viscosa akeake
Griselinia littoralis kāpuka / broadleaf
Griselinia lucida puka / broadleaf
Hedycarya arborea porokaiwhiri / pigeonwood
Hoheria sp lacebark
Laurelia novae-zelandiae pukatea
Myrsine autralis māpou / red matipou
Myrsine salicina toro
Pennantia corymbosa kaikōmako
Peraxilla colensoi mistletoe
Pseudopanax arboreus five-finger
Pseudowintera axillaris horopito
Pseudowintera colorata horopito / pepper tree
Schefflera digitata patē