Exploring the neighborhood nettle patch

Several weeks ago I got restless and wanted to look at something that wasn't comprised of pixels, so I walked down our neighborhood bicycle path to the local middle school's athletic fields.  They abut a farmer's cornfields, and the verge between the properties has a variety of native plants and wildflowers.  I had visited this area frequently a couple summers ago to harvest milkweed leaves to feed our monarch caterpillars, but since our own milkweeds now serve this purpose, I hadn't been back for a while.

On this recent visit, I noticed a patch of differently colored plants at the corner behind the soccer goal.  The photo above shows thigh-high grass at the edge of the field, and behind that some waist-high darker plants in front of the barbed wire.  It looked familiar, so I waded in (after tucking my pants legs inside my socks to keep any ticks on the outside of my pants...)

The plants next to the fence were nettles, which to a butterfly enthusiast can be a gold mine, because they are host plants (food for caterpillars) for at least three varieties of colorful butterflies.  I bent down to take a closer look, and sure enough virtually every plant had holes eaten in the leaves, and more importantly, many of them showed this characteristic pattern (click for fullscreen):

The leaf stem has been partially cut, which causes the leaf to droop.  Then the edges of the leaf have been "sewn" together with silk, protecting the inhabitant inside from predation by critters like the spider (on the outside of the folded leaf), wasps, and parasitic flies.

Now, the question was - could I harvest some of these to take home to raise and release the butterflies?  The first question to be answered was what kind of nettles were these??  There are many nettles, but only two important categories - stinging nettles (genus Urtica) and "false" (nonstinging) nettles (genus Boehmeria).   I'm not knowledgeable enough to know the difference.  If they were false nettles, I could just grab some stems to take home; stinging nettles require a modicum of caution.

One way to sort this out would be to take sample leaves and submit them to the horticultural extension service at the University of Wisconsin and wait for a report.  That would entail a certain expense and would be too slow for my purposes.

The second method would be to get some good photos of the leaf leaves and stems and then consult some plant databases via the Internet.   Less reliable than a professional opinion, but much cheaper and a bit faster.

I took a half dozen photos, then leaned in to snap one of a caterpillar that had emerged from hiding and was climbing a stem.  My camera was set for a macro closeup, but the wind was whipping the plants back and forth, which made the process difficult, and then...

OW OW OW!!!!   BURNS LIKE FIRE !!!!

Diagnosis made.  Quickly (instantly), cheaply (free), and reliably (no doubt in the world these were stinging nettles).  Despite the name "Urtica" for the family, the reaction to these is not urtication (itching), but a violent inflammatory reaction manifested by welts:

The pain subsided by the time I had walked home, and the lesions on my upper arm faded that night.  I returned with long sleeves, leather gloves, and 6-inch forceps, and managed to bring back some leaves with caterpillars.  The downside of raising these little fellas is that unlike milkweed leaves or cabbage leaves, those of the nettle are thin and dry out in a day or so.  Combine that with the voracious appetite of the cats, and it means I had to return every two days or so and risk the integrity of my integument to get them more food.

The reward has come the last two days; so far I've released five of these very handsome Red Admirals (Vanessa atalanta):

These are not rare or endangered butterflies; they are actually quite common in all 50 states here.  But it has been an interesting experience to raise them; I'll post more re their life cycle some other time.

Addendum:  Scanning EM of stinging nettle hairs.

Second addendum:  An article at Salon explains how to harvest stinging nettles and prepare them for eating in a salad:

Nettles lose their sting when exposed to concentrated heat, and they are edible and extremely nutritious, being rich in vitamins A and C, as well as potassium, iron, magnesium and calcium... Even though I'm wearing gloves, my childish fear lingers and I can't bring myself to touch the leaves; with these gingerly methods it takes me five or 10 minutes to fill the colander... When it comes time to actually taste one, I hesitate. Maybe just a little longer, I think, and prod the ropey mass of greens for the umpteenth time. I turn down the burner, stalling for time... Maybe it's the aftershadow of the sting, but the nettles taste strangely alive -- fibrous and tingly, with a hard-to-articulate flavor. Nutty is as close as I can get.