Occurrence of Dasypodia selenophora in Southland.
[Read before the Southland Branch of the Royal Society, November 24. 1938; received by the Editor, December 22, 1938; issued separately, September, 1939.]
During 1937–38 the Province of Southland enjoyed a very warm and dry summer, followed by a comparatively mild winter and warm spring. Undoubtedly the climatic conditions were beneficial to various forms of insect life, and from being sufficiently noteworthy to attract newspaper paragraphs last summer, the white butterfly (Pieris rapae) has now increased in numbers so as to become almost common with the advent of the 1938–39 summer.
Various species of the family of Elateridae are to be found everywhere in increasing numbers, and the lighting of fires at night to attract and destroy the night-flying Porina moths was advocated by the Provincial Executive of the Farmers' Union (Southland Times, 29/10/38). The larvae of the Diamond-back moth (Plutella maculipennis) took a heavy toll of the field crops and the vegetable gardens last summer, but have not made an appearance yet this year.
Dasypodia selenophora. Guenée.
My attention was first drawn to the occurrence of this moth by a paragraph which appeared in the Southland Times of 22nd October, 1938. This read: “An unusually big moth of striking colouring was brought into the Times office yesterday. It was found on the property of Mrs. Pont, Colac Bay. With a wing-spread of nearly two inches, the moth was of a rich dark brown colour, and on each wing was a distinct blue ring.”
On 25th October I received three specimens—one from Ryal Bush, one from Otatara, and one from Invercargill. On the 26th another was reported to me from Kew. On the 28th two more, and on the 29th I found one in my own room in South Invercargill at 10 p.m. Other specimens were forwarded to the Southland Museum, and the table below gives the date, locality and number:—
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|22/10/38||Times report of Colac Bay specimen||1|
|25/10/38||Ryal Bush, Otatara and Invercargill||3|
|26/10/38||Kew specimen reported||1|
|28/10/38||Castle Rock and Invercargill||2|
|8/11/38||Shown two and received report of several others, all from Invercargill||2|
|17/11/38||Kew, two specimens; a third received by post without any name or locality||3|
|19/11/38||Shown three more by Dr. Burns-Watson, of Invercargill, collected by his son, who reported two others||5|
Thus it will be seen that over a period of between three and four weeks the moth has appeared in many parts of Southland, and I was told by a workman from the Milford Sound District that the moth was fairly common in that locality.
In the Southland Museum collections are six specimens of D. selenophora, but no record exists to say where they were obtained, by whom, or on what date. Four of the six mentioned are in the Pascoe collection and may have been obtained locally many years ago but must remain doubtful owing to lack of data.
Colenso records having witnessed the metamorphosis of D. selenophora (Trans. N.Z. Inst., vol. 11, page 300).
Meyrick describes the moth in his monograph of the New Zealand Noctuina (Trans. N.Z. Inst., vol. 19, page 38) and gives localities “Napier Richmond and Christchurch in January; apparently not common. Occurs commonly in Eastern Australia.”
Hudson in his New Zealand Moths and Butterflies, 1898, pp. 35 and 36, gives localities Auckland, Napier and Wellington in the North Island and at Nelson, Richmond and Christchurch in the South Island, and further states that the perfect insect appears in January, February and March, and that it is rather a rare species.
Tillyard in his Insects of Australia and New Zealand, 1926, p. 443, slates that the Noctuinae are not represented in New Zealand except by introduced species. He says that D. selenophora is common in Victoria and Tasmania and not uncommon in parts of New Zealand.
Hudson in his Butterflies and Moths of New Zealand, 1928, pp. 80 and 81, describes Dasypodia as an Australian genus probably of one species and states that the antennae in the male are ciliated He gives as New Zealand localities “generally distributed throughout the North Island and in the South Island it has occurred at Nelson, Richmond, Hokitika, Christchurch, Invercargill and at Dog Island in Foveaux Strait. He says the larvae are fully grown about the end of January and the perfect insect appears in February, March and April, but is rather a scarce species. “Hibernated individuals are sometimes found in October and November, at which time the eggs are deposited.”
Summary And Conclusion
Apparently D. selenophora is not a native of New Zealand and must have been introduced from Australia originally.
The usual appearance of the moth is given as January, February, March and April.
Hudson says hibernated specimens are sometimes found in October and November, the months in which the present occurrence has taken place.
The larvae feed on Acacias and these trees are planted in many parts of Southland.
An examination of Acacias near and in Invercargill failed to reveal any larvae.
No Acacias are present in the Milford district so far as I am
aware, but the kowhai (Sophora microphylla) and various species of Carmichaelia represent the Leguminosae.
The antennae in the males are ciliated. All the specimens received at the Southland Museum are females and one deposited several scores of eggs in the tin in which she was confined.
The question arises as to how the present occurrence of this moth has taken place. Three solutions seem feasible and any one might suit the present case:—
1.That the moths may be hibernated individuals as described by Hudson. The dry summer of 1937–38 and the comparatively mild winter and early spring following would be favourable in this respect. The date of the occurrence is as given by Hudson.
2.That the moths may have arrived here by flight from Australia, in which case one would expect to find them in the Milford district, the nearest land in New Zealand to Tasmania and Eastern Australia.
3.That the eggs of the moth may have been introduced by some means and the resultant growth of the larvae and the metamorphosis taken place in this country. Hardwood poles from Australia are often landed at the Bluff, and the eggs, which are small and seed-like, could be introduced in this way.
Without further knowledge, the question must remain unanswered, and it will be interesting to see if a large hatch takes place from January on in 1939, for many moths must have had opportunity to deposit their eggs, and the number captured probably represents a very small percentage of the total present in Southland at this date.
Since writing the above I have received five more specimens on the following dates:—
|22/11/38||Three specimens, one from South Hillend, and two from Te Tua||3|
|24/11/38||Two from Gladstone||2|
This brings the total up to 34, and Dr. Burns-Watson has reported to me of the presence of several more. I was also told by a friend that the conductor of the Children's Session at Station 4YA, Dunedin, has received a great many more from various parts of Southland and has been giving a radio talk on them during a part of the programme. I have since verified this report.
I was told about the same moth whilst on a visit to Stewart Island in March, 1939, and identified a specimen as D. selenophora. The time of the appearance on Stewart Island coincided with that on the mainland. Further evidence came to hand of the appearance of the moth in the Milford Sound district, but no specimens were forthcoming, although my informant described the moth and readily picked it out when shown a tray of mixed moths.
A close watch was kept in many parts of the Province during January, February and March of this year (1939), but no specimens were seen or heard of.
I tried to hatch out eggs laid by some of the specimens sent in to the Southland Museum, but was unsuccessful.