Isturgia penthearia

Delta Geometrid at Melba, ACT

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Identification history

Isturgia penthearia	31 Jan 2021	donhe
Isturgia penthearia	31 Jan 2021	ibaird
Unidentified	25 Jan 2021	kasiaaus

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8 comments

ibaird wrote:

25 Jan 2021

Yes, an unusual grey, worn form of the species I suspect.

kasiaaus wrote:

25 Jan 2021

I think this might be Epidesmia perfabricata. The colour matches better and the hind wings on this one showed no orange.

ibaird wrote:

25 Jan 2021

I considered E perfabricata too, but I wasn't convinced given the shape and position of the main forewing line, which seemed to me to match E. chilonaria better.

kasiaaus wrote:

26 Jan 2021

I wonder if you could have another look (I added two more photos that you may not have seen). The third photo shows a bit of the underwing and there is no orange. It was also quite a fresh moth and not a worn one.

ibaird wrote:

26 Jan 2021

This is a male judging by the antennae. Referring to the underwing pattern for E. chilonaria given by Moths of Victoria on their supporting disc (Part 4), there is orange on the top side of the hindwing but not on the bottom side of the hindwing. There is also orange on the underside of the forewing and a conspicuous black blotch provided the plain hindwiing is not obscuring the yellow forewing underside. On the underside of the forewing the entire wing is not yellow, the wing near the costa and almost a third of forewing towards the tip remains plain. Similarly, the entire top side of the hindwing is not yellow the trailing edges are plain and a large are toward the tornus of the hindwing (normally exposed when the moth is at rest) also remains plain. I think its entirely plausible that the yellow of the hindwings for E. chilonaria is invisible in your photos because it is obscured by overlapping forewings or hindwings. Also there are clear dots along the forewing mainline topside in E. perfabricata and along its forewing hindmargin which appear to be absent here. Nevertheless, to attract a third moderator's opinion on this identification I will add the ID of Epidesmia (genus) to reflect the uncertainty.

donhe wrote:

26 Jan 2021

The hindwing tornal area of E. chilonaria is brown, and consistent with your 3rd photo.

ibaird wrote:

31 Jan 2021

Not Epidesmia genus, this is Isturgia penthearia.

kasiaaus wrote:

31 Jan 2021

Thanks Ian. I was worried about this one ;-)

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