...................................... Click on photo to enlargeThe Silver-bordered Fritillary is the smallest of the fritillaries with silver spots on the underwings. They are members of the brush-foot family of butterflies, which means they have shortened front legs like a preying mantis, or T-Rex, if you will. But fritillaries restrict their diet to nectar as adults and strictly violets as caterpillars.
In fact, it is the rarity of the host plant that accounts for the rarity of this species. You see, Silver-border Frits only like Northern Bog Violets, Viola nephrophylla, which in turn only like wet places. And since we have been terribly fond of draining our wet places, we have a real shortage of bog violets - and Silver-bordered butterflies.
Spreading its wings to a maximum of two inches, Silver-border Frits have a distinctive white edging. Size wise, and color wise, it would be easy to mistake this rarity for a common Meadow Fritillary- but a thorough scan of the border tells the whole story.
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We are looking at winged gold!
......................... Photo by Su Snyder Silvery Crescentspot and Pearl Crescent
There are several other confusing species among these golden wings of summer. Also in the two-inch-and-under category is the deeper shaded Silvery Crescentspot (left). They are members of the brush-foots too, and are in the same genus as the Checkerspots. For quick identification, I look for several round open cells in the spots on the hind wing. This is when a careful study of the dorsal edge makes all the difference!
The smaller butterfly to the right is our gold standard of measurement, the Pearl Crescent. Stretching out at 1-1.5 inches, Ohio's most common butterfly feeds on asters as a larva, and nectars at flowers as an adult.
Get to know your Pearl Crescent well, and if something looks a little too big, or a bit too bright- you'll know it is time to call out the Border Patrol!
Cheryl-
ReplyDeleteWe've recently learned that Viola nephrophylla is much more widely distributed in Ohio than previously thought. Up until last year, we thought it was restricted to the limestone shores of Lake Erie Islands and the Catawba Peninsula. Now we know that it is in fens too, and it is also most likely grows in huge numbers at Resthaven Wildlife Area. I know there are silver bordered frits at places that we don't have records for Viola nephrophylla. If this species is exclusive to nephrophylla, it might lead us to more populations of the plant. What makes me a little suspicious is that in the past botanists themselves don't agree on exactly nephrophylla is- some same it is a "real" species, others say it isn't, but now I think the consensus has shifted back to the "real species" side of the equation.
Cheers,
Tom
Thanks Tom- I love a good botany response!
ReplyDeleteAs I scoured for information re: S-B Frits, most books use the default "violets" as host plant. We know they are far more specific than that- but one good source sited "Northern Bog Violet." Some friends indicated to me the likely host plant is Lance-leaved Violet, Viola lanceolata. That makes total sense to me, but I have not been able to verify that elsewhere. I guess my experts are as good as any other, and may be better than others - for Ohio's butterflies.
I would be interested in interfacing the S-B frit population and the Lanced-leaved Violet population. Although, beware of "Correlation Science"...oh, how statistics can lie!
great post - full of good information - i have never seen this flutterby and now i know why(smile)- next time i am in the western basin or the islands i will have to keep my eyes open
ReplyDelete