In late August of 2021, I was out in Southeastern Utah visiting one of my Spadefoot Toad pools. The pool had Sunflowers emerging from the tadpole water. This water was the only source of Sunflowers in the area, most of the ground was too dry.
While I was looking at the tadpoles, I kept seeing what I thought were Hummingbirds out of the corner of my eye.
I looked more closely – not Hummingbirds, but Moths! There were two White-lined Sphinx Moths (Hyles lineata) working the Sunflowers.
Here’s a photo of the Sunflower patch. You can see that the Sunflowers are fairly sparse, and there’s not another patch nearby.
The moths would zip around, almost too fast to watch, then they would seem to freeze in the air as they hovered in front of one of the flowers. The dark and light markings on their wings were very prominent – the moths almost looked like they were black-and-white when I was watching them.
The Moths had a rosy-pink band on their hind wings that was faintly visible sometimes, depending exactly on their wing configuration as they hovered. The fast-moving blur of their wings made the pink band seem even more pale than it is in these photos.
One of the things I’ve noticed in looking at Sphinx Moth photographs like the one below is that there is often a sharp angle in the Moth’s proboscis, rather than a smooth curve along the whole length of the proboscis.
I’ve read that Octopuses will make similar sharp bends in their legs when they are moving them precisely. The sharp bends essentially create “pseudo-joints” in their limbs. The explanation I’ve read for the phenomenon in Octopuses is that the pseudo-joint decreases the degrees of freedom of their limbs, making it easier to coordinate and control their limbs precisely. I’m fascinated by that idea, that a creature would temporarily decrease the flexibility of their limb to make it easier to control.
I wonder if that need to precisely control/coordinate the tips of their probosces is why Moths tend to have that angle when feeding. I’ve not read that anywhere, so I may be way out in left field with that idea.
The Moth’s proboscis is a surprisingly complex organ. It’s comprised of two semi-tubular halves that are held together by hooks that form something like a zipper.
In its relaxed state, the Moth’s proboscis coils up tightly. The Moth extends its proboscis via muscles in the proboscis. When the tip of the proboscis is in the flower’s nectary, there is a sac in the Moth’s head which expands and contracts to pull the nectar up the proboscis.
I just can’t believe these things work at all.
Sunflowers are Composite flowers – a single Sunflower is comprised of many smaller flowers. The dark disk part of the Sunflower’s “flower” is comprised of numerous disk flowers. Those disk flowers are where the Moth is going to get its nectar.
You can imagine how precisely the Moth needs to hover and position its proboscis to visit the individual disk flowers. I’m also amazed at how well the Moth must be able to see, to differentiate the disk flowers from each other.
In the photo below, you can see that the Moth is tipping its head slightly to the right, off of the main axis of its body, as it accesses one of the disk flowers. I was surprised to see this, I did not know that Moths would tip their heads like that.
One of the host plants that is listed on Wikipedia’s page for Hyles lineata is Purslane – Portulaca spp. There was a lot of Purslane growing on the surrounding desert floor. I wonder if that’s what the Moth’s caterpillars had been eating.
I had a grand time identifying this Moth and looking up information on it. One of the most enjoyable aspects of the research was that I stumbled across photos and descriptions of the White-lined Sphinx Moth’s caterpillars.
Way back in 2001, when I lived down in Tucson, I had come across some large Sphingid caterpillars (photos below).
At the time, I could only identify these caterpillars as “Sphinx Moth Caterpillars”. Based on the information I found on Bugguide.net’s page on Hyles lineata, I’m fairly confident that my mystery Sphingids were White-lined Sphinxes.
I love it when stuff comes together like this, and when a mystery from twenty (argh!!) years ago gets solved.
Sources:
Bugguide.net’s wonderful entry for Hyles lineata. I’m continually amazed at how useful this site is.
Wikipedia’s entry for Hyles lineata. How any one site can have the diversity and depth of information that Wikipedia has…well, I’m speechless. A magnificent site.
German Sumbre, Graziana Fiorito, Tamar Flash and Binyamin Hochner. Octopuses Use a Human-like Strategy to Control Precise Point-to-Point Arm Movements. 2006. Current Biology.
