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Contents > Butterflies > Resident > Ringlets > Forest Ringlet

Forest Ringlet

 

Dodonidia helmsii

Distribution & Status Forest Ringlet Distrubtion Map

Endangered Lewis Pass north in local colonies. Decreasing population, especially near cities. Wasps are the main suspect. There has being no sightings in the Waitakere or Rimutaka Ranges in the past 20-30 years.

NatureWatch NZ
Observations map

Scientific Classification More info

Family

Nymphalidae

SubFamily

Satyrinae

Tribe

Satyrini

SubTribe

Coenonymphina

Genus

Dodonidia

Taxon

helmsi

Also Known As;

Beech Forest Butterfly, Helms' Butterfly and Silver streak

Description

Another one of New Zealand's colourful butterflies and probably the most likely butterfly to become extinct as population status appears on the decrease. Generally known as a 1 year lifecycle, but some believe that there could be a 2 year lifecycle, due to 2nd and 5th instar larvae being found in November in highland areas. Also there has being several recordings outside of the January to February general flight time, all of which where in highland areas. This could be due to the previous year being 'good' or 'bad' and the larvae developing sooner or later then average. The Forest Ringlet is also parasitised by a undescribed Tachinid fly of the species Pales (family: Tachinidae, subfamily: Goniinae), which lays eggs on the foodplant to be eaten by a larva a some stage. The first sign of infection is when the parasite makes a brown 'breathing hole' at the rear or thorax of the larva. The parasite will then emerge after consuming the larva in the days before pupation to pupate itself. There has also being a documented case of a tiny wasp in the Trichogramma genus parasitising a ovum of the Forest Ringlet. This made the ovum go black all over, then the imago wasp emerged from the shell of the ovum a few weeks later.

Ovum  In English

Laid singularly on underside of leaf away from the edge. Pale with hint of green when laid, which lasts for the first few days, but then darken to a yellow-green. 3 days before hatching, the shell becomes transparent letting you see the eyes and jaws of the developing larva. The next day the whole head darkens the upper part of the ovum. It is a spherical ovum with about 50 fine vertical ribs, which appear to towards the top half of the ovum, the bottom part being smooth or pitted. The adhesive is usually visible. They hatch in about 22 days. The shell is eaten by the newly hatched larva for it's first meal.

Larvae  In English

After hatching it is pale green with a black head. Long, green and stout in the middle with short legs. The second instar is reached after about 30 days (if winter hasn't arrived), this is when the head and tail grow bifid projections and the black head is discarded. This leaves it looking very similar to the 3 Tussock Ringlet species. The larvae live about 10 months and have 5 instars. The larvae hibernate (probably a diapause as no activity has being recorded in winter months) after the 2nd or 3rd instar in May at the base of the foodplant until the following spring. They have lines on sides and top of body that are darker and lighter then the body. A newly hatched larva may not start eating until 2 or 3 days old, then it will prefer young shoots. They are night feeders, so are easier to find the elongated notches through the leaf it makes in the leaves of the foodplant then looking for the larvae itself as they are well camouflaged and usually spend the daytime head-down about 3cm below the notch they are presently eating. This can take several days as they are slow at doing anything. Before pupating, they hang for about 3 days slowly losing their colour before moulting into the pupa. Grows up to 35mm when fully grown.

Pupa  In English

Brown to green and stout with reddish outline on wing cases. Hangs upside down by cremaster in some nearby sheltered spot. Pupation lasts about 20 days.

Imago  In English

The imago has a 40-64mm wingspan. It is generally larger in the north, with the average wingspan for the Central Plateau is 53mm, while those around the Dun Mountain area of Nelson are nearer 44mm. This maybe due to a mineral belt that also seems to have a dwarfing effect on Janita's Tussock as well. It is a fast and jerky flyer that likes to sunbathe near the tree tops. In full sun they keep their wings wide open, but quickly close them if there is any disturbance, including wind. The female generally comes nearer the ground to search for sites to oviposit. One of it's favourite nectars is from the Kamahi tree (Weinmannia racemosa). Both males and females have the same wing markings, however the male has a long and slender abdomen while the female has a shorter and stouter abdomen. The imago lives from 3-4 weeks, only flies on sunny days.

Habitat Forest Ringlet Habitat

Generally lives in the tree tops of Beech forest glades and edges. It can be found from sea level up to Tussock level (1,000-1,200 metres).

Food Plants

Cutting Sedge (Gahnia pauciflora) in lowland North Island and Giant sedge Gahnia procera in the Central Plateau and the Gouland Downs, Nelson. In the remainder of the South Island, it generally prefers Narrow-leaved bush tussock (Chionochloa cheesemanii) and Snow Grass - Hunangamoho (Chionochloa conspicua). It is also recorded on Cutty Grass - Rautahi (Carex geminata).

Lifecycle
Lifecycle of the Forest Ringlet

Contents > Butterflies > Resident > Ringlets > Forest Ringlet