DoomsdaysCW[Thread] So, here's a problem that may already have a solution...! Apparently, #ElmZigZagSawfly, an invasive species, is spreading in the #Northeastern US and can defoliate #ElmTrees (which have been making a comeback from #DutchElmDisease), and has adapted to switch tree species. However, #AsianLadyBeetles, another invasive species and the natural predator of Lantern Flies (and aphids and other pests), is also spreading! I know we always have some Lady Beetles inside our house, and instead of killing them, my plan is to catch and release them outside... So they can hopefully do their thing! (And yes, we have quite a few Elm trees, descendant of a survivor tree that fell down recently, in our tree stand).
Elm Zig Zag Sawfly
"The first confirmed detection of the elm zigzag sawfly in North America occurred in August 2020 in Québec, Canada (Martel et al. 2021; https://www.invasivespeciescentre.ca/first-confirmed-sighting-of-a-new-invasive-in-north-america-elm-zigzag-sawfly/). Canadian authorities were unable to determine the introductory pathway or amount of time the insect had been present [Invasive Species Centre].
The Canadian population was not the only outbreak on the continent, however. Earlier the same year, the tell-tale feeding pattern – zigzags on the tree’s leaves — was observed in Frederick County, Virginia (northwestern corner of the state). Since no specimens were recovered, identification was not confirmed. A year later, specimens collected from the same confirmed the presence of EZS [David Gianino, State Plant Regulatory Official (SPRO) of Virginia, pers. comm.]. Additional surveys that summer led to detections in eight additional Virginia counties [K. Oten blog].
Also in the summer of 2021, symptoms were observed in Lehigh County, Pennsylvania. Again, however, the absence of a specimen prevented formal identification [K. Oten blog]. In 2022, official detections were made in Pennsylvania, North Carolina, Maryland, and New York [NCSU extension]. The New York infestation might have spread naturally across the St. Lawrence River from the Canadian population [https://www.wwnytv.com/2022/10/03/new-pest-affecting-elm-trees-st-lawrence-county/].
In 2023, outbreaks were detected in Ohio, Vermont, and Massachusetts [NCSU extension map]. In 2024, Wisconsin found EZS in several counties [University of Wisconsin extension]. Neither the Canadian Food Inspection Agency nor the [Canadian] Invasive Species Centre reports on EZS’ more recent status in Canada."
[...]
"Since most trees can recover from sporadic or minor defoliation events, the state extension programs say control efforts are often not warranted. Furthermore, since EZS is a new pest species, little is known about effective management. Results of experimental treatments using various pesticides or biopesticides are reported from Hungary (Blank et al. 2010), Romania (Fătu et al. 2020), and Virginia [NCSU extension]. The University of Wisconsin and University of Massachusetts extension service mention several predators present in Europe. The University of Massachusetts extension service notes that the multicolored Asian lady beetle, Harmonia axyridis, which preys on EZS in Serbia, is also present in Massachusetts (actually, it is widespread in the United States); its impact on elm zigzag sawfly in Massachusetts is uncertain."
Learn more:
https://www.dontmovefirewood.org/pest_pathogen/elm-zig-zag-sawfly/
#SolarPunkSunday #InvasiveSpecies #NaturalSolutions #Trees #NoPesticides #DontTransportFirewood #CheckYourVehicles #SaveTheTrees
First confirmed sighting of a new invasive in North America: elm zigzag sawfly – Invasive Species Centre
Adult EZS on an elm leaf where they lay their eggs. Photo: Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org. By: Sarah Sinon, Research Analyst Intern With its signature feeding pattern, […]
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