I discovered the beautiful Humming-bird Hawk Moth (Kolibrievlinder) hovering above flowers in a Dutch garden

Humming-bird Hawk Moth visiting flowers
31Aug 23 SRX06805A.JPG©Gert Korthof

This summer I was photographing butterflies in De Tuinen in Demen gardens, The Netherlands. These gardens have literally hundreds of flowering plant species. Unexpectedly, I found myself chasing a Humming-bird Hawk Moth, Macroglossum stellatarum (Dutch: Kolibrievlinder) hovering above the flowers. 

The butterfly was quite difficult to capture because it constantly moved from one flower to the next, and never sat down on a flower. Typically, they hover a few centimeters above a flower and stick their tongue out to enter a flower and quickly move to another flower. This is a very unique behaviour for a butterfly. Most butterflies sit down on a flower for some time. This exotic butterfly certainly deserves its name: it behaves like a hummingbird! It is really acrobatic to enter such a long tongue into flowers while hovering.

Later, when selecting the best pictures, I discovered the long tongue. At that moment I remembered the cover illustration of Mark Ridley's Evolution textbook:

cover Mark Ridley Evolution 3d edition

Ridley writes [1] that Darwin had seen specimens of the orchid Angraecum sesquipedale which has a very long spur. A nectar spur is a hollow extension of a part of a flower. Darwin speculated that a butterfly with a very long tongue must exist. But at the time he did not know such a species. Twenty years later such a butterfly was discovered: the hawk moth Xanthopan morganii pollinating an orchid. The butterfly I photographed, Humming-bird Hawk Moth, is not the same as the one on the cover of Ridley's Evolution. It is another genus. but it belongs to the same family [2]. The plant species my Humming-bird hawk moth visited is not an orchid. Now it gets interesting. Did my butterfly visit the 'wrong' flowers? There are no flowers present that fit the tongue of my Humming-bird Hawk Moth? Upon further inspection of my pictures I noted that the flowers also had a rather long spur:

Size of flower spur indicated with arrow.
31Aug 23 SRX06798A.jpg©Gert Korthof

But this spur is certainly not as long as Darwin's orchid. So, the particular plant species and my Humming-bird Hawk Moth don't seem highly adapted. They did not co-evolve.

This is a mystery. Are there plant species in the Netherlands or elsewhere in Europe which are better adapted to the Humming-bird Hawk Moth? Plant species with a very long spur? I don't know. More observations are needed. In the Netherlands our butterfly is often seen on a common garden plant: Buddleja davidii (butterfly bush, vlinderstruik) native to China and Japan. The problem is that in observation.org and waarneming.nl it is not required to identify the plant species when submitting an observation of a butterfly [3]. It is difficult to identify the plant species from the pictures. Above that, waarneming.nl discourages users to upload non-native plant species and it could be that precisely cultured garden varieties are visited by the Humming-bird Hawk Moth!

Another unique feature of this 'moth' are the eyes. They are looking at you:

He is looking at you!
SRX06802.jpg©Gert Korthof

It looks like a human eye!

Then its wings: rather exceptionally for a moth, its wings have orange patches!

Finally, another mystery: what about pollination? Since it doesn't sit down on a flower, the only point of contact is its tongue! Clearly, this is a wonderful and unique butterfly, or should I say a moth?

 

Additional nice pictures

https://waarneming.nl/observation/290848030/

https://waarneming.nl/observation/290782391/

Sources

• Wikipedia: my hummingbird moth: Hummingbird hawk-moth; 
• Dutch wikipedia pages: Kolibrievlinder, Vlinderstruik.
• the genus of my butterfly: Macroglossum is a species rich genus.
• Darwin's butterfly: Xanthopan morganii;  Darwin's orchid: Angraecum sesquipedale
• wikipedia page Nectar spur contains list of plants with nectar spurs.
  
• Gene Kritsky (2001) DARWIN's Madagascan Hawk Moth Prediction, American Entomologist 37:206-210. I could not find the full text version anymore.
  
• Robbie Gonzalez Darwin Predicted This Animal's Existence Decades Before Its Discovery, May 13, 2015. Contains many further interesting details.
• What about the amount of (junk) DNA of this butterfly?  "Note that ecology and physiology can also matter. Some organisms—such as carnivorous plants and hummingbirds—may face stronger selection to purge excess DNA. Consistent with the increased selection, these organisms typically have smaller, sleeker genomes." ( source )
• Location where I spotted the hummingbird hawk moth: De Tuinen in Demen The Netherlands.

 

Notes

1. Mark Ridley (2004) Evolution, third edition, page 617. Ridley discusses the case in the paragraph 22.3 'Insect-plant coevolution'. But also that the case is more complex than just the coevolution of insect tongue length and flower spur length.
2. Family: Sphingidae (pijlstaarten) is a very species rich family and the genus Macroglossum has nearly a hundred species.
3. Buddleja davidii  (vlinderstruik), Lavandula species (lavendel), geranium, Valeriana spec (rode valeriaan), Phlox, Verbena officinalis (ijzerhard) are visited by the Humming-bird Hawk Moth.