Buttonbush (Cephalanthus occidentalis, family Rubiaceae) has become a favored native in Ohio landscapes. The medium-sized shrubs sport large, dark green, glossy leaves. The button-like name-sake flowers are highly attractive to pollinators, although their passing resemblance to the SARS-CoV-2 virus is a bit disconcerting.
Buttonbush is relatively free of insect and disease issues. It’s highly tolerant of poorly drained soils and is commonly found in Ohio, thriving in wetlands and at the edge of ponds. However, it does not do well at the dry end of the soil moisture spectrum.
Yesterday, I returned to a buttonbush planting in a local county park where last year, I had observed bizarre leafmining activity. The affected plants also had new shoots that were wilted, dead, and blackened. The symptoms mimicked freeze damage, which was odd, given my visit was in mid-July.
However, observing the shoot damage was key to identifying the culprit behind the leafmining damage. I posted my observations in a BYGL Alert titled “Buttonbush and 'Herbivore Specialists'” [ https://bygl.osu.edu/node/2526 ].
Two native moths belonging to the genus Mompha (family Momphidae) are “specialists” on buttonbush, meaning they do not feed on any other host. They are M. cephalanthiella and M. solomoni. Both are tiny moths, called “microlepidoptera,” which is a nod to their diminutive size and not a defined taxonomic group.
M. cephalanthiella is commonly referred to as the Buttonbush Leafminer. Although the literature notes that the natural history of this moth is poorly understood, the caterpillars apparently remain true to their common name and only feed as a leafminer, with their handiwork described as “blotch mines.” I’ve never observed damage from this moth in my part of Ohio.
M. solomoni caterpillars shift their feeding behavior from leafmining to shoot boring. Thus, observing the double-damage was key to identifying this moth as the culprit producing leafmines and shoot dieback on buttonbush in southwest Ohio. Indeed, even though the moth has no approved common name, I made the case last year that it should be called the Buttonbush Leafminer/Shoot Borer.
The buttonbush leafminer/shoot borer has three generations per season, with the first generation having a distinctly different lifestyle compared to the second and third generations. First-generation caterpillars bore into the developing shoots in the spring. Their damage causes the new shoots to wilt, die, and turn black.
I visited the site yesterday because I didn’t discover the infestation last year until it was too late to photograph shoot-boring caterpillars. In fact, I was almost too late yesterday because many of the damaged shoots had already been abandoned.
However, I discovered that caterpillars push frass out of the holes in the shoots. So, observing the pellet-like frass around the holes is a good indicator that the unusual-looking caterpillars are active.
Once the caterpillars complete their larval development in the shoots, they emerge to pupate in the leaf litter. Some of the second-generation moths that rise from the leaf litter will lay their eggs on the shoots. The resulting caterpillars continue to produce the shoot-boring damage.
However, the vast majority of the moths lay eggs on leaf midveins to initiate a leafmining lifestyle practiced by second and third-generation caterpillars. The caterpillars first produce short, frass-filled, serpentine leafmines that look like brown “squiggles” extending from the midvein. The serpentine leafmines may lead directly to blotch mines. Or the caterpillars may migrate to a new location to produce another meandering leafmine that’s slightly longer.
Eventually, the caterpillars produce frass-filled blotch mines. Based on what I found in the literature, apparently, the Buttonbush Leafminer Moth caterpillars do not produce serpentine mines. Of course, they also do not bore into the new shoot.
My BYGL Alerts on the Buttonbush Leafminer/Shoot Borer are not intended to raise alarms. At this point, I consider the native moth to be more of an oddity rather than an emerging issue. However, I have some concerns that mistaking the shoot-boring symptoms for freeze damage may cause us to miss infestations. This is why I’m urging readers to take a closer look.
BYGL Alert Bonus Content
Life as a specialist has its rewards and penalties. This section is a reward to readers who have remained awake and Alert to this point.
Buttonbush is relatively free of pests and diseases. Members of the genus Cephalanthus use an array of secondary plant metabolites for plant defense, including alkaloids, terpenes, and phenolic compounds.
It’s a family business. Members of the Rubiaceae family produce several well-known alkaloids, like the antimalarial quinine produced by Cinchona trees (Cinchona spp.), and caffeine produced by coffee plants (Coffee spp.). It’s an eye-opener.
However, deploying a chemical defense against herbivory is a two-edged sword. What happens if natural selection imbues an herbivore with the ability to handle the chemical defense? Not only is the plant no longer protected, but the plant’s chemical defense tilts the scales by driving away other herbivores. The “specialist” gains a competitive advantage.
On the other hand, specializing in making a living on a single plant species is also a two-edged sword for an herbivore. As the host goes, so goes the specialist.
One of the best examples of the price paid for a complete dependence on a single host is the Karner Blue butterfly (Lycaeides melissa samuelis). The butterfly can only make a living on the Wild Blue Lupine (Lupinus perennis). The butterfly became endangered when habitat loss caused a severe decline in the lupine. It was a twist on the Monty Python quote, “Your life or your lupines!” From the butterfly’s perspective, it was your lupines and your life.
The Monarch Butterfly (Danaus plexippus) gained “specialist” status with Milkweeds (Asclepias spp.) by gaining an ability to handle the steroidal cardenolides found in the sap. The penalty is that now it’s tied to its host.
But evolution never sleeps. Natural selection has gifted a plethora of other insects with the ability to utilize milkweeds, sometimes at the expense of the monarch. It’s a game of thrones.
Ohio is home to two native sawflies, belonging to the family Tenthredinidae, which specialize in feeding on the leaves of buttonbush: Pseudosiobla excavata and P. cephalanthi. Let the hunger games begin.
Selected References
Birnbaum, S. S. L., & Abbot, P. (2018). Insect adaptations toward plant toxins in milkweed–herbivores systems–a review. Entomologia Experimentalis et Applicata, 166(5), 357-366.
https://doi.org/10.1111/eea.12659
Bruzzese, D. J., Wagner, D. L., Harrison, T., Jogesh, T., Overson, R. P., Wickett, N. J., ... & Skogen, K. A. (2019). Phylogeny, host use, and diversification in the moth family Momphidae (Lepidoptera: Gelechioidea). PLoS One, 14(6), e0207833.
https://doi.org/10.1371/journal.pone.0207833
Grundel, R., Pavlovic, N. B., & Sulzman, C. L. (1998). Habitat use by the endangered Karner blue butterfly in oak woodlands: the influence of canopy cover. Biological conservation, 85(1-2), 47-53.
https://doi.org/10.1016/S0006-3207(97)00165-1
Hall, S.P., Sullivan, J.B., Petranka, J.W., Feldman, T., George, D., … & Howard, T. (2025). The Moths of North Carolina [Internet]. Raleigh (NC): North Carolina Biodiversity Project and North Carolina State Parks.
https://auth1.dpr.ncparks.gov/moths/index.php.
Wagner, D. L., Adamski, D., & Brown, R. L. (2004). A new species of Mompha Hübner (Lepidoptera: Coleophoridae: Momphinae) from buttonbush (Cephalanthus occidentalis L.) with descriptions of the early stages. Proceedings of the Entomological Society of Washington, 106(1), 1-18.
