4/24/2021: The confusing nomenclature of Lygaeus turcicus
Several years ago I began offering large milkweed bugs, Oncopeltus fasciatus. Although hardy captives, due to their messy habits and the frequency of required care with old techniques I would often lose the colony sporadically for various reasons. In part, I suspect this was due to the pathogen Leptomonas wallacei, which causes significant problems in Oncopeltus fasciatus. I do still culture the species, but currently am working on a resistant strain or finding a practical way to create a clean, uninfected culture.
Despite this, when a large milkweed bug colony thrives, it really, really thrives, and their success on an easy diet of shelled sunflower seeds despite their wild host being milkweeds made me curious to try raising other true bugs on the diet.
Last summer I found some odd bugs on my Heliopsis helianthoides. They looked like small milkweed bugs, but the coloration was a suaver orange, more similar to large milkweed bugs. I collected some, threw them on sunflower seeds, and soon had a nice colony. Very nice. However, after my Oncopeltus experience I grew suspicious a pathogen could or would terminate the culture, so I destroyed the culture.
On Easter I found a few overwintered adults crawling around my parents’ native plant beds, so I collected a few in a ziplock bag with some paper towel. Paranoia crept in again, and I left them in said bag til they perished… but not before one laid eggs in a corner. I collected these eggs, set them up as I had before, and can happily say I now have a fresh batch of adults ready to start a veritably pathogen-free culture!
These bugs have an interesting history, being confused with Lygaeus kalmii for many years despite their very different coloration and host plant. In recent years the label “false milkweed bug” has been slapped on them to differentiate them, but I don’t think this is a proper title. It’s quite misleading, as the monikers “small milkweed bug” and “large milkweed bug” both mention the obligate hosts of those species… But Lygaeus turcicus doesn’t use the “false milkweed plant” (which to my knowledge, isn’t even a common name for any plant). Instead, they use Heliopsis helianthoides… the false -sunflower-.
Adding to the complexity, in Michigan members of the plant clade that Heliopsis helianthoides belongs to include… The true sunflowers, genus Helianthus, and the rosinweeds, genus Silphium. This plant clade is endemic to the Americas, and considering the very high species diversity I would assume it has been here a very long time. Milkweeds and their kin, however, arrived from Africa circa 20 million years ago; relatively recently in geological time.
I am thus suspicious that, given all of these factors, the ancestral diet of that bug clade might be sunflowers and their close relatives in North America. (Though, if the sunflower group arrived more recently than milkweeds, I would reverse that relationship!).
For these reasons, I will be labeling Lygaeus turcicus as the “false sunflower bug” when posted for sale, as it’s far more accurate to tie the species to its solo host plant than to a paraphyletic group of bugs with a completely different clade of hosts.
-Kyle