Some of the bugs that I was most disappointed in not being able to net during the trip I talk about in Some Musings on a Recent Excursion were several clearwing moths, because I am deeply fascinated by the little wasp mimics in the family Sesiidae. My photos weren’t that bad, but, at least superficially, many of the moths in Synanthedon look the same, and I didn’t even try to identify them. But then, when I was writing the profile of Koenigia davisiae , I saw that Synanthedon chrysidipennis uses it as a larval host, and that reminded me that some of those little clearwing moths were on Davis’ knotweed. So I looked Synanthedon chrysidipennis up on BugGuide, and saw that they had that same orangey gold coloring in the wings as did the moths in my photos.
Now I was excited, because my favorite thing in doing these profiles is when I can post both a plant and the insect that uses it as a larval host back to back. So I jumped at the chance to go back up to Mt. Hood when (shameless bit of name dropping here) Merrill Peterson asked if I could collect some of the little Euphilotes butterflies that I’d seen on the last trip, and for which I had asked him to confirm identification, since he’s doing a study of those buckwheat blues. So I asked Pam’s permission to borrow her Kia (which gets almost twice the gas mileage of my van), and headed out early the next morning.
This time I didn’t forget the net (or a couple quarts of fluids and lunch) and I spent the first couple hours chasing little Euphilotes, but once I had a good variety of specimens I started hunting for Davis’ knotweed and Synanthedon. And though I did find an abundance of the knotweed, the few clearwing moths I saw were too quick for either my camera or my net. Until I got to a little basin of pumice sand maybe an acre in diameter, where the conditions were so unfriendly that there was nothing growing there except for Koenigia davisiae, and there were my clearwing moths. I probably saw at least 50 of them in the hour I hung out there. Most of them were still pretty flighty, so after spooking a few trying to get close enough for good photos, I switched to attempting to capture them first, and finally got a couple.
After that I put down the net and started stalking them with the camera. And ended up being rewarded by finding a mating pair that let me get within a couple feet. I was over the moon, and took waaay too many photos, but I was just thrilled that a plant that I hadn’t even heard of a few days before, and which I had initially dismissed as a weed, was hosting these beautiful clearwing moths, with which I had also been unfamiliar, and that part of the process of making new Synanthedon chrysidipennis moths was happening right before my eyes, a whole intimate relationship of flora and fauna playing out before the lens of my camera. This is the kind of thing I live for as a recreational naturalist!
Description– Medium sized (20-23mm) clearwing moth that is mostly black, with yellow palps and legs, yellow on the sides of the thorax, yellow bands on the abdomen, and wings that are bordered in orange red.
Similar species– Other Synanthedon don’t have this much orange in their wings
Habitat– Alpine and sub alpine meadows containing its host plants, which seems to be knotweeds, especially Koenigia davisiae .
Range– “At higher elevations from British Columbia south to Utah and California.” Species Synanthedon chrysidipennis – Hodges#2578 – BugGuide.Net; in the PNW it’s range is probably very similar to that of Koenigia davisiae , i.e., Cascades, Olympics, Siskiyous and Rockies.
Eats– “The larvae have been recorded as boring in the roots of Polygonum davisiae and Polygonum sp. (Polygonaceae). Henne notes that several specimens were observed in Smokey Valley, Tulare County visiting flowers of Achillea lanulosa Nutt. (Asteraceae).” Species Synanthedon chrysidipennis – Hodges#2578 – BugGuide.Net; I personally observed several of these adults nectaring on Calyptridium umbellatum
Eaten by– Larvae are undoubtedly parasitized by the larvae of various wasps and flies, and larvae and adults are probably preyed upon by insectivores of all classes (at least, in the case of the adults, ones not put off by their wasp mimicry), but I can find nothing specific.
Adults active– “Adults can be seen, often in large numbers, from late June through early August flying about the host plants in alpine meadows. — William H. Taft, 19 August, 2016” Species Synanthedon chrysidipennis – Hodges#2578 – BugGuide.Net
Life cycle– “Pupation takes place in cocoons in the larval burrow near the crown of the host plant, or the larvae may construct silk-lined tubes extending from the exit hole in the root to the soil surface to provide a means of escape for the mature pupa…- William H. Taft, 19 August, 2016” Species Synanthedon chrysidipennis – Hodges#2578 – BugGuide.Net
Etymology of names– Synanthedon is probably from the Greek words for ‘with the flowery one’, ‘flowery ones’ being a poetic name for bees, and may be a reference to their wasp mimicry. But I can’t corroborate this. The specific epithet chrysidipennis is from the Greek word for ‘a bit of gold’ and the Latin word for ‘wings’, and should refer to the golden tinted wing margins, except that (according to my wife and George Engelhardt, as he stated in no.190 (1946) – Bulletin – Biodiversity Heritage Library) they are more red orange than gold. Perhaps Boisduval was color blind like I am, because I thought they looked orangey gold.