Tuesday, April 17, 2012

Red Admiral Invasion

I'm freshly back from an interesting trip to the great state of Virginia and the beautiful city of Winchester - renowned for its Shenandoah Apple Blossom Festival. This event will celebrate its 85th year in a few weeks; unfortunately given the early spring, their apple trees will have shed their blossoms by then. I was there to speak at a new and interesting conference called Tomorrow's Landscapes, held at Shenandoah University. It was fun and infomative; among the better run of these sorts of things and it was great to see acquaintances such as Jeff Lowenfels all the way from Anchorage, Alaska, and Doug Tallamy from Delaware.

The relatively short drive over to Winchester took me through five states: Ohio, Pennsylvania, West Virginia, Maryland, and Virginia. Before leaving Ohio last Friday, I was seeing LOTS of red admiral butterflies, Vanessa atalanta. I saw some more along the drive to Virginia but not as many as were fluttering around my home state.

Bold and pugnacious, a showy red admiral alights on your blogger. These brush-footed butterflies stage periodic large, conspicuous northward migrations, such as happened over the last week in Ohio and elsewhere in this part of the country.

One day last week, I glanced out my office window - I work in a very urban area - and six or more of the butterflies were swirling around the blossoms of a flowering crabapple tree. I was even seeing red admirals flying through traffic on very busy Morse Road. Our Ohio Birds listserv was awash in comments about the proliferation of these butterflies, so much so that I was awaiting the appearance of one of the self-appointed listserv police, to make one of their bah humbug "those aren't birds!" comments.

A red admiral at rest with its wings held up is not nearly so conspicuous as they are when the wings are spread and flattened, revealing the showy orange-red bands. In fact, in this position, the butterfly becomes an outstanding leaf mimic.

Dave Horn, an entomologist and current president of the Ohio Lepidopterists, made the following statement on our Ohio Birds listserv in response to all of the red admiral reports: " The red admiral has periodically appeared in large numbers since the early 19th century. While there is no universally accepted explanation for these increases it seems most likely that they are related to high overwintering survivorship in the southern USA followed by favorable conditions for northward movement. This year we have had both a very mild winter (in Ohio and southward) and an early spring and I suspect the large numbers we are seeing reflect those weather conditions".

Sums it up nicely, I think.

Red admirals, in all their beauty, are spawned from plants in one of our most maligned botanical tribes, the nettles. I made this photo a few years ago, of a communal "nest" of red admiral caterpillars that had formed a tent shelter from the leaf of a tall nettle, Urtica procera. At least during their early instars, the caterpillars congregate within the rolled-up leaf, emerging under cover of darkness to ravage the nettle foliage.

Here's a red admiral chrysalis, which I also found on a nettle plant. I've found red admiral caterpillars several times, always on nettles. And always the stinging species. Not everything in the Urticaceae (nettle) family has stinging hairs, and apparently red admirals utilize non-stinging species, but I've only found them on the plants that you'll quickly regret brushing up against.

Not a bad strategy, if you can evolve yourself into it. Most critters probably shun nettles, same as we do, and that includes potential caterpillar predators.

Knowing that such a stunning butterfly as the red admiral requires the lowly nettle as an essential part of its life cycle might stimulate one to view these stinging plants with a fresh perspective. The plant in this photo is a tall nettle, Urtica procera - same species that I've found red admiral larvae on - and it isn't so ugly after all.

Plant some nettles in your yard and who knows, you might raise a crop of admirals. Or better yet, as I believe it is the Weedpicker who says, sneak into your neighbor's yard and plant them there - that's close enough to still enjoy the butterflies!


Unknown said...

I was at Camp Libbey last week, and literally had hundreds of Red Admirals for company. I was worried that I'd step on them!

Nettles, eh? Okay, that one nasty patch near our drive can stay. I'm itching just thinking about the nettles. Your pictures nearly caused welts to appear on my typing fingers!

nina said...

A little bit of an aside from butterflies, but I had the rare occasion to sample some nettle tea last week. It was wonderful! I did notice some red stripes across my shoulders that evening, but other than that....

Anonymous said...

I live in Saginaw, MI, and have noticed the population explosion of Red Admirals this spring...especially over the last week (even though our early spring retreated to normal highs and lows for awhile).

I found it very odd, as they were going back and forth through our backyard, stopping at the apple trees, napping on the warm south facing brick of our house.

I was driving down a very busy road today, and every 5-10 feet, one would swoop past me. I was in awe! I asked my ten year old fellow nature buff if he noticed, and he lit up. "Yes!!! Everywhere I look, I see one!!!"

We had a mild winter here in Mi (as in other states), but I found an Ontario newspaper article about this....an expert mentioned that when there are mild winters, the Red Admiral does not migrate to the lower South......

That would explain the population boom, which I am loving. I wish they ate aphids, though, because I think we are having a pop boom of those too this year....I've found them on every plant in my perennial garden!

Jim McCormac said...

Thanks for sharing these other reports, and I would like to try some "urticaceous" tea sometime, Nina! Thanks for sharing that; didn't know about it!

alex said...

Before I began learning to forage wild plants, I shunned and avoided the stinging nettle for years! Now I seek them out wherever I go and have to admit that the twinge of excitement at sighting the first urtica dioica shoots of spring is akin to the one i get when staring down my first spring warbler! This is one of the most delicious as well as nutritious plants in the forager's canon, and its habit of growing in especially large patches makes it an easy sustainable catch. Harvest the top few bracts with gloves and scissors (before they flower) and then pop them into some boiling water for just a few minutes, which destroys the spines and breaks down the formic acid. Then use them as a side dish, chop and add to stir-frys, puree into a hearty soup or make a nettle pesto! These greens are ridiculously rich in calcium, iron, magnesium, manganese, potassium and other trace goodies. They also have the highest documented protein content of any green! I've heard some foragers speculate that the urtica/laportea clan may have evolved their stinging hairs because without them, they'd be eaten to the ground in minutes! In short, I can only applaud these caterpillars on a great choice of host plant!


As always, click the image to enlarge At the onset of last Monday's aquatic expedition (perhaps more on that later) to Rocky Fork ...