Saturday, August 19, 2023

Evening-primrose Moth


A familiar, widespread and oftentimes very common wildflower, the Common Evening-primrose (Oenothera biennis). The colorful buds in the center will burst into flower the following day.

Primrose flowers open at dusk, flower through the night and the following morning, and largely close up by early afternoon. I departed for an epic day of bird photography yesterday at 5 am, and as it got lighter towards dawn, I noticed many large drifts of primrose along the roadsides as I neared Lake Erie and the western marshes. Whenever I see this plant in flower, a particular and very special moth comes to mind.

Later that morning, I was slowly cruising down a country lane near Ottawa National Wildlife Refuge. Scattered patches of primrose dotted the roadside, and I was keeping an eye on those when I spotted a pinkish anomaly in one of the flowers. The flower in question is the topmost blossom on the tall plant in this photo.

Closer inspection revealed a pair of Evening-primrose Moths (Schinia florida) tucked into the flower! Nearly the entire life cycle of this beautiful pink and yellowish moth plays out on primrose flowers. The adults roost in or on the flower buds during the day, will take nectar from the flowers at night (as do many other moth species), and the caterpillars eat the flower buds. The latter burrow into the ground to pupate.

A pair of Primrose Moths on flower buds makes for a particularly colorful scene. This species has but one brood a year, and now is the time to search for them. Just try to keep an eye on primrose flowers, looking for pink spots in flowers. Morning is best, when the flowers are fully open, and the moths are more exposed.

Primrose Moths seem inexplicably rare, given the abundance of their host plant. I have looked at thousands of primrose flowers over the years, and this is only the third time I have found the moth. The site where the moths in this post were had many other primrose plants in the vicinity. Despite checking hundreds of nearby flowers, no other moths could be found.

Common Evening-primrose is part of a complex of Oenothera species that may not yet be understood very well. Some of them hybridize, and at least some species appear to be of relatively recent origin. It may be that some varieties/forms/species may vary profoundly in chemical composition, and the Evening-primrose Moths and its caterpillar phase are tightly tied to a rarer form of the primrose. Pure speculation of course, but there's some reason(s) why this colorful moth is apparently fairly rare. A check of iNaturalist bears this out. There are less than 20 records from Ohio, and while the moth does become more frequent in other regions, overall, the records are scattered and often few and far between.

PHOTO NOTES: I made these images with the Canon R5 (it's the only camera I want to use anymore) and the superb Canon 100mm f/2.8L macro lens. I used flash from the 600 speedlite for some images, as it was a sunny day, and the light was somewhat harsh. Flash can help mitigate that. Almost all images were at f/13. If no flash was used, the ISO was 400 and whatever shutter speed gave me a correct exposure. Flash on, it was ISO 200 and 1/200 shutter speed.

The moths in the flower were shot in situ. Once that was done, I transferred them to a primrose that sported the colorful flower buds. I do not know for a fact that Primrose Moths roost on flower buds but given their similar coloration it seems plausible that they would. Whatever, I wanted that shot. It was an easy matter to gently coax the moths onto my finger. When I presented them with the flower buds, they scrambled right onboard with little prompting and posed beautifully. After that shoot was complete, I got the moths back on my finger, put them up to another primrose flower, they pushed inside, and I left them be. I have found that the fuzzier/hairier the moth, the more mellow and easier to handle it is. These Primrose Moths reinforced that rule.

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