‘Acrocercops’ zorionella (Hudson, 1918)
Parectopa zorionella Hudson, 1918
This moth belongs to the subfamily Phyllocnistinae, and is not related to true Acrocercops, which belong to another subfamily. Hence the apostrophes around the genus name.
Biostatus and distribution
This endemic moth forms leaf mines in its endemic host plants, large-leaved species of Coprosma, and is found in the North Island and South Island. It appears to be restricted to native ecosystems, even occurring in small reserves of native ecosystems in urban areas.
Conservation status: Widespread, not threatened.
Life stages and annual cycle
Leaf mines with caterpillars can be found every month of the year. There are 3 or 4 generations a year in warmer regions of New Zealand (e.g. Auckland),and fewer generations in colder areas.
Adult moths are long and narrow at rest and about 5-6 mm long. The moth holds its wings roof-like over its body. The dark wings have bluish reflections and small white marks forming three narrow bands. It is presumed that the adult male and female moth are attracted to each other and mate. The female moth then lays eggs.
Caterpillars and leaf mines
Eggs are laid singly on the underside of leaves and have a shiny shell. The caterpillar hatches from an egg and tunnels directly into the leaf forming a narrow mine just under the epidermis (skin) of the underside of the leaf. After some distance the caterpillar tunnels through the leaf and forms a mine under the epidermis on the upper side of the leaf. The mine is initially narrow and serpentine, but as the caterpillar grows the mine gradually widens and may form a large blotch. As it gets bigger, the caterpillar moults (changes skin). When fully grown the caterpillar is about 6-7 mm long. The caterpillar is white with a flat brown head that has protruding jaws in front. It uses the jaws to bite off pieces of internal leaf tissue at the edges of the leaf mine. The caterpillar feeds mainly on the sap (juices) from the plant cells, ingesting very little solid tissues. The mine contains the black frass (insect faeces). The legless caterpillar has prominent segments of the body that help it move through its mine.
Cocoon and pupa
When the caterpillar is fully grown, it makes a thin, silk-lined chamber in the leaf mine. The location of the cocoon often shows on the outside as a raised area on the upper surface of the leaf. The caterpillar moults into a pupa, which is white at first and then turns brown. Shortly before moth emergence, the colour of the wings and legs can be seen. At the apex of the head is a sharp spike. This is used by the moth to break through the cocoon and skin of the leaf. When the moth is ready to emerge, the pupa wriggles forwards, makes a hole in the leaf surface, and forces most of itself out of the leaf. At the rear end of the pupa are two hooks (see drawing). The hooks grip the silk cocoon and hold the pupal skin while the moth pulls itself out.
Moths of this leafminer are similar in appearance to other moths in the genus that are also leafminers. The moths can be distinguished by the bluish reflections from the shiny forewings and the rather few silvery markings. The white markings in the Pseudopanax miners (i.e. 'Acrocercops' species) are more extensive and scattered.
This is the only moth that makes long serpentine mines in large leaved Coprosma species. The caterpillars of the karamu shoot borer, Tanaoctena dubia Philpott, 1931 (Lepidoptera: Yponomeutidae), make small mines in fleshy leaves of some species of Coprosma. While a weevil, Notinus cordipennis (Broun, 1915) (Coleoptera: Curculionidae) makes a blotch mine in small-leaved Coprosma species such as Coprosma foetidissima, a species that is also host to the coprosma leaf mining moth.
The presence of the moth in a habitat can be recognised by the presence of its leaf mine.
No predators of this moth have been reported. However, birds and spiders are likely to prey on the moths.
At least two kinds of tiny wasps (Hymenoptera) parasitize larvae of the karamu leafminer. In the summer, caterpillars are killed by a single larva of one of the wasp species. Before pupation this wasp larva builds columns of black faeces on either side of itself, so that the pupa has some protection from crushing. In the winter and spring leaf mines can be found with several white larvae or black pupae of a second wasp parasitoid. This wasp species may kill the caterpillar or the pupa.
The karamu leafminer forms leaf mines in species of Coprosma (Rubiaceae), with large and medium sized leaves. Mines are more commonly found in very young plants and saplings of broad leaved Coprosma species growing alongside forest tracks.
The caterpillars feed on the internal tissues of the leaf. They tunnel through making mines that are visible from the upper side of the leaf.
|Common Name(s)||Scientific Name||Family||Reliability Index||Biostatus|
|Tree coprosma, Mamangi, Māmāngi||Coprosma arborea Kirk||Rubiaceae||10||endemic|
|Thin leaved coprosma, Aruhe||Coprosma areolata Cheeseman||Rubiaceae||9||endemic|
|Stinkwood, Hūpirau-ririki, Hūpiro, Karamū, Mikimiki, Mingimingi, Naupiro, Pipiro, Piro||Coprosma foetidissima J.R.Forst. & G.Forst.||Rubiaceae||10||endemic|
|Kākawariki, Kanono, Kapukiore, Karamū-kueo, Kueo (fruit), Manono, Pāpāuma, Raurēkau, Toherāoa||Coprosma grandifolia Hook.f.||Rubiaceae||10||endemic|
|Shining karamu, Kākaramū, Kākarangū, Karamū, Kāramuramu, Karangū, Patutiketike||Coprosma lucida J.R.Forst. & G.Forst.||Rubiaceae||10||endemic|
|Coprosma macrocarpa Cheeseman subsp. minor A.P.Druce ex R.O.Gardner & Heads (2003)||Rubiaceae||10||endemic|
|Glossy karamu, Kākaramū, Kākarangū, Karamū, Kāramuramu, Karangū||Coprosma robusta Raoul||Rubiaceae||10||endemic|
|Round-leaved coprosma||Coprosma rotundifolia A.Cunn.||Rubiaceae||6||endemic|
|Wavy-leaved coprosma||Coprosma tenuifolia Cheeseman||Rubiaceae||10||endemic|
Plant-SyNZ: Invertebrate herbivore-host plant association database. plant-synz.landcareresearch.co.nz/.
Watt MN 1920 (1919). The leaf mining insects of New Zealand. Transactions and Proceedings of the New Zealand Institute 52: 439-466.
Robert Hoare for information about this moth.
The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.
1 July 2018. NA Martin. Remove Coprosma repens as host plant and photo of leaf mine.
1 August 2017. NA Martin. Host plant table updated and photo of another host plant added.