Schinia interspecies mating?

Yesterday I learned that there is a PhD student at Penn State working on a revision of the gall wasp genus Antistrophus and that he needs collections of galls on Pyrrhopappus. I volunteered to help look for them, having seen some in the past.

While I was at work today I went for a walk down the street, as is my habit. I noticed plenty of Pyrrhopappus along the side of the road, so I began looking. I found quite a few, and collected about a dozen.

As I was walking along and inspecting the flowers I noticed one of my favorite little elusive moths, Schinia mitis, which hosts on this plant. The moths visit the flowers in the morning, lay their eggs in the center and then fly away or snooze in the flower as it closes for the day. The caterpillars eat the flowers and then, I assume, they pupate in the soil or inside the spent seed head on the ground. Since I was looking closely at each of these flowers I started coming across a few mating pairs of Schinia mitis, which was a first for me.

A lot of these moths would dart as soon as I would get close. Combined with the wind and their small size I would quickly lose them. However, the mating pairs would stay in place, even when I used my hand to steady the flowers in the wind. Because of the flighty nature, I was videoing each flower that I could tell had an occupant, not knowing if it would be a single moth that quickly disappeared or a mating pair that would stay in place. In one of these cases I came upon a mating pair where one of the two moths was much more vividly colored than the other. At the time I chalked this up to sexual dimorphism or natural variability.

However, when I returned to my desk at work I started looking at my photos a little more closely. If the other pairs demonstrated sexual dimorphism it was on a much more subtle scale than this pair. Furthermore, this one vividly colored moth looks identically like another species in the genus, Schinia bina.

The moth in question has a deep raspberry basal third, moderately pink median, and yellow terminal third. Also, the three sections are separated by two narrow and scalloped bands of white. The ventral sides of the wings are patterned. All of these characteristics are consistent with S bina and not with S mitis.

S mitis has a tan wing superimposed with magenta or brown V mark in the basal half of the wing and a diagonal mark in the lower half of the wing. The ventral sides of the wings are dark and solid, not patterned.

A final observation: when the wind blew the wings of the moth in question the abdomen was exposed and it appears to be quite large, which leads me to believe this was the female of the pair. I don't know if that has any implications, but I presume it might. For instance, if the female is the one who emits the pheromones among Schinia moths, then perhaps she was in the wrong place (the host plants of a different species) at the right time to make this pairing happen. Rather than a male S bina having traveled to this location after having sensed the pheromones of a different species.

I have shared the photos with Chuck Harp (@cehmoth), who specializes in Schinia and other Heliothinae.

I don't know how common interspecies mating or hybridization are among moths or specifically those of this family, but it's not something I have witnessed before. I also did a little searching today and have not come across many examples online. (one example)

IF this truly was a case of interspecies breeding, does this imply something about their phylogeny? Could they be related closely enough that their pheromones are similar?

I do note that Schinia bina's host plants are a bit of a mystery. It has been recorded on Verbesina encelioides during the late summer brood, but this spring brood that is in flight in April must be using a different plant. Could they be using Pyrrhopappus?

I did not collect any of these moths, although now I am sort of wishing that I had. I will be watching for this moth again, and also be looking for the caterpillars. Perhaps one flower will have some odd looking caterpillars that don't match the normal red and white striped caterpillars of Schinia mitis...

For reference, here are the MPG pages for each species.
Schinia mitis
Schinia bina

Posted on Απρίλιος 23, 2024 0851 ΜΜ by zdufran