What is Eating Garry Oak (Quercus garryana) Leaves?

Observations by Iain McKechnie:

On 27 May 2018, I observed holes in the leaves of Garry Oak trees (Quercus garryana) on the trail of Mount Tolmie Park. I wondered if a fungus or an insect was causing the defoliation. In mid-November 2018, I noticed that the trunks of several oak trees in the vicinity of Mount Tolmie and on city streets of Saanich were being wrapped with sticky tape and have many insects stuck to them, not sure if this is related to the leaf consumers, but seems likely.

LEO BC coordinator Tom Okey wrote:

In an online article entitled Insects: Life and Death on the City’s Foliage, Janis Ringuette reviewed various pests of Victoria's foliage, and stated that, "According to Dr. Michelle Gorman, the green inch-worm larvae of the winter moth (Operophtera brumata)...is responsible for the damage." The photos shown in that article are similar to the photos provided by Dr. McKechnie in the present LEO Post. This article is part of an online chronological history of Victoria, BC's Beacon Hill Park from 1842 through 2009. I am reaching out to Michelle Gorman, Integrated Pest Management, City of Victoria, for comment this observation.

On November 21st and 30th of 2018 I recorded on iNaturalist my observations of swarms of the invasive Winter Moth (Operophtera brumata) in the Garry Oak forests of my neighborhood in Victoria---the west side of Cedar Hill Park. See my observations on the 21st and 30th. The observation on the 30th was less certain due to my photo of only the ventral side of the specimen, and so it is identified as Operophtera sp. These swarms seemed to contain unusual abundances as if it exemplified an infestation of introduced species. This is the species that Dr. Michelle Gorman identified as the culprit of the defoliation of Garry Oak trees in the Victoria area.

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