Green Longhorn Moth

[Troels]

A big swarm of theese danced in the afternoon sun. Sometimes they rested a few seconds on a beech leaf before taking aff again.

You must wonder how they are able to navigate with such a pair of wires. Very inconvenint in windy weather.


Full size at flickr

The English name is a little strange since it is entirely black with very glossy wings.

[rjlittlefield]

The English name is a little strange since it is entirely black with very glossy wings.

Adela reamurella? Other images on the web show individuals that have a distinct green sheen in certain illumination. Is this the same beast?

--Rik

[Troels]

I do not claim to be an expert, but of the around 20 species in Denmark of the family Adelidae only two are mainly black in color. The other is Adela cuprella, but this has completely white antennas while A. reamurella has black basis and white more distant.

I also read, that the color of the wings is somewhat variable and sometimes difficult to determine. Se here how the reflections in the scales give different impressions.


I can see hints of green blue and violet.

I have also compared with the pictures in the Danish citizen science database "Fugle og Natur" (menans Birds & Nature). Many of the photos there are similar to mine. See here

But of course there could be errors - like the obvious errors in the collection from Google you linked to.

[Edit:] I have sent the pictures to evaluation at the experts at Fugle & Natur.
Always nice to be corrected.

[Lou Jost]

The common name, "longhorn" is also the English name for cerambycid beetles.

[Troels]

Lou,
Yes, you are right. I have now changed the topic title to "Green Longhorn Moth".

And a Danish lepidopterologist has confirmed that is is Adela reamurella.

[Lou Jost]

No matter what their name is, they are amazing creatures. I had not known about them before seeing your pictures, though I seem to have dim childhood memories of seeing something similar back in the northern US when I was growing up.

[Troels]

Yes, and amazing to see them dance. The antennas make big curved lines glittering in the sun like spider web. At first glance I had no idea what kind of animal it was. The black fur and the shiny wings made me think of rubberflies.

First time I saw them there were hundreds dancing in a limited area. Unfortunately I did not have my camera at hand. The pictures are taken the next day where the number of insects was much lower. It was impossible for me to get decent shots of flying moths.

[Lou Jost]

Do they dance around a female?

[Troels]

All the individuals I photographed resting on leaves in between their dancing were males. The antennas of the females are much shorter.

From what I have read only the males are dancing. The females then pick the one they like best. A mating behaviour also known from some species of birds (f. i. the wader called Ruff (Calidris pugnax).

Other insects using long, thin appendices for dancing are the Mayflies. But their 3 "threads" start from the hind end, kind of tails. They also make a beautiful sight.

It is tempting to imagine that the threads besides their visual sex appeal also have an aerodynamic function in the dance by slowing down the descent after an energy consuming ascent. A very low weight animal will feel the air resistance much stronger, than we do. Small spiders use a single thread as a kite/parachute.

[Shilden_72]

If they're the same species I sometimes see when traveling there, then yes, they do dance around females. And I do think they're the same species, you can't really mistake these antennae for something else!

[MarkSturtevant]

Very interesting!

[anvancy]

Lovely documentation!

[Troels]

Thanks to all for looking and commenting!

I continued the study in my stacking studio, so look for really close-up fotos of the wing in the other forum .