The Little Blue That Couldn’t
HERE’S A CASE OF UNREQUITED AFFECTION between a pair of little butterflies known as Silvery Blues (Glaucopsyche lygdamus). In the top two rows of images, the female, her wings folded up, is minding her own business on a leaf. The male is fluttering and flashing, approaching and retreating — an aerial dance that basically amounts to his giving it his best shot at the singles’ bar.
Butterflies generally reproduce in four stages. First, is location. They find one another, often visually. Next, is approach. He makes his moves, which is what we’re seeing here. If it seems to be going well, the male can then step it up by directing pheromones toward the female, which might help seal the deal. A female can reject these advances, however, by raising the tip of her abdomen or, in some case, refusing to reciprocate with pheromones of her own. In this instance, she sat there, apparently indifferent to his gyrations.
After all his displaying, which went on for about three minutes at a site in Maine last week, the female finally flew off. He landed nearby and flashed his azure wings at me (bottom left in the montage). That final image is of a female — perhaps the same one that played hard to get — laying eggs on vetch about 15 minutes before all this transpired. So perhaps she had had an earlier copulation with another male. (Among some butterfly species, the male can prevent a second copulation by inserting a plug — called a sphragis — in the female’s mating tract so that his are the sperm that count when she lays eggs. How ruthless.)
Had this encounter gone better for this particular male, had he scored, er, I mean reached the final phase of reproduction, the two would have linked their abdomens so that he could deposit his packet of sperm and nutrients (a spermatophore), which she stores in an organ called the bursa copulatrix. (I swear — when I form my heavy metal band, I’m gonna call it Bursa Copulatrix.)
In this case, because I have no photo of a consummation, I’ll leave you instead with a copulating pair of related little butterflies, Bog Coppers (Lycaena epixanthe), with a portion of the male’s spermatophore visible. (He’s gotta cover that thing!)