cloudy with a chance of graupel

sodium parties and sulphur butterflies

A lovely interlude in Theodore Gray's "sodium party" page:

We had wet down about a 15 foot radius all around, and true to expectations, there were a series of secondary explosions as balls of sodium ejected by the main explosion hit the ground. Unfortunately I was taken aback by the explosion and jerked the camera, so you can't see them. That's one reason the later videos came out better: I used a tripod.

I had planned to hose down and maybe neutralize the driveway the next morning, but in a fascinating display of nature, the driveway was full of little yellow butterflies the next morning.



I've read that male butterflies collect sodium as a present for their mates, and they sure seemed to like mine, so I decided to leave it. I'm surprised they liked what must be a fairly basic solution, but then maybe it's just neutralized decades of road acid.

According to the popular radio entomologist May Berenbaum from the University of Illinois, I was right about the butterflies. She writes:
"They're called sulfur butterflies (in the family Pieridae) and the general consensus is that they are indeed after sodium, which is transferred to females in the spermatophore or sperm package.
Here are some references about the phenomenon:
Adler, P. and D. Pearson, 1982. Why do male butterflies visit mud puddles? Can. J. Zool. 60: 322-325.
Arms, K., P. Feeny and R.C. Lederhouse, 1974. Sodium: stimulus for puddling behavior by tiger swallowtail butterflies, Papilio glaucus. Science 185: 372-374.
Smedley, S. R. and T. Eisner 1996. Sodium--a male moth's gift to its offspring. Proc. Nat. Acad. Sci. 93:809-13.

And then it's back to the kabooms.

(I wonder, in coastal areas do the butterflies frequent the seashore?)