This summer, the elm zigzag sawfly was located in Delaware County in July and Franklin County in August.
“This is the first detection of the species in Ohio,” ODNR Division of Forestry, Forest Health Program Manager Tom Macy said.
The elm zigzag sawfly can cause defoliation, but the full impact is not yet known, according to ODNR. The insect has a distinct feeding pattern that results in zigzag lines on elm leaves.
There are no reports of the elm zigzag sawfly causing elm trees to die at this time, ODNR said. The Division of Forestry is continuing to survey the insect and management options are being reviewed.
The caterpillar-like insect has larva up to half an inch long and is light green. Larvae feed exclusively on elm tree leaves and spin loose, net-like cocoons that attach to the leaves, according to ODNR. In the fall, they form more solid-walled overwintering cocoons on the ground in leaves or soil.
Adults elm zigzag sawfly are not seen as often as the larvae, but are a quarter inch in length and are shiny black with wings.
A few elm zigzag sawfly larvae were discovered on trees in a Delaware County nursery in July. The insect was confirmed in Franklin County on Aug. 18, according to ODNR.
Anyone who finds suspected elm zigzag sawfly or signs of an infestation should try to get a good picture and report the sighting to the ODNR Division of Forestry by calling 614-265-6694.
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