I recently observed odd leafmining activity on wild grape (Vitis spp.) growing in a local park in southwest Ohio. The leafmines were serpentine, named for their snake-like appearance, and they were filled with a dark line of excrement (frass). The leafmines ended in elongated expansions where the leafminer was no doubt pupating.
However, the pattern of the frass-filled leafmines on some leaves went beyond simply meandering across the leaf. James (2022) accurately described such unusual leafmines as looking like “scribbles.”
The likely culprit is a tiny moth belonging to the genus Phyllocnistis in the leafmining moth family Gracillariidae. Beyond that, the taxonomy gets wonky. A search of the online literature yielded two possible contenders: P. vitifoliella and P. vitegenella. Neither of these native moths has accepted common names. I’ll call them Grape Serpentine Leafmining Moths.
Bugguide, hosted by the Iowa State University Department of Entomology, has long been my go-to for identification of insects, spiders, and other arthropods. Searching their database using the scientific names of the suspected serpentine leafmining moths yields: “vitegenella complex.” Seeing the word “complex” means there’s evidence of more than one species, but the taxonomy has not yet been sorted.
Regardless, the grape serpentine leafmining moth that I found appears to be an oddity in Ohio that’s confined to wild grape. According to grape aficionado, Dr. Gary Gao (OSU Extension Specialist, Small Fruit), this is not a pest commonly found in vineyards in our state.
On the other hand, the grape serpentine leafmining moths bear monitoring. A similar leafminer appeared in vineyards in Washington State in 2020. James (2022) wrote, “Leafminer damage on wine grapes was first reported from vineyards in the Tri-Cities area in September 2020. We determined that the damage was caused by a new, undescribed species of leafmining moth in the genus Phyllocnistis. This species is the first leafminer pest to be recorded damaging commercial wine grapes in North America.”
Websites and References:
Bugguide Webpage for vitegenella complex (Phyllocnistis vitegenella complex)
https://www.bugguide.net/node/view/2503042/bgpage
Charley Eiseman’s BugTracks:
https://bugtracks.wordpress.com/2020/06/19/the-yard-lists-part-16/
James, D.G., (2022). Survey and Monitoring of the Incidence and Abundance of New Leafmining Pest of Wine Grapes in Eastern Washington, Final Report 2021-2022, Washington State Grape and Wine Research Program. 13 pgs.
