Grindelia Gall Quest: keep your eyes peeled for more of these!

This all started with @naturesarchive posting this observation from Stanislaus County CA this month!:
I am in the east bay and I regularly see tons of Grindelia sp. but had not noticed any leafy galls on them before. I assume since the plants are so common they get passed over often by iNatters in favor of rarer wildflowers and flowers with more pollinators. Interestingly enough I was at a project site in Alameda County this week surrounded by Grindelia sp. and once I actually looked I saw leafy galls for the first time! So excited and wanted to post, but they were on private property, so I figured I would try to find them at a public location such as EBRPD Brushy Peak Regional Preserve which is somewhat nearby in the same habitat.
In iNat, I looked up which trails people had seen Grindelia, and set off this morning to find more leafy galls. I looked at 20+ Grindelia plants before finding my first one!
Looked at 20 more Grindelia plants and found a second!
The third plant with a gall I decided I would split it open to see if it was indeed an insect creating the gall as suspected, and if the gall actually had a chamber--I was in luck:
Chamber and larva confirmed!
One more gall from the day:
I bet there are many more leafy galls on Grindelia throughout the Bay Area and Central Valley! Keep your eyes peeled! (See a dried up version from Jan 2020):

Posted on July 25, 2022 05:15 AM by chyroptera chyroptera


@merav @garth_harwood Look at these leafy Grindelia galls! Keep you eyes peeled for more!

Posted by chyroptera over 1 year ago

@catchang @damontighe @kueda Keep your eyes peeled for this leafy gall on Grindelia sp. in the Bay Area and beyond!

Posted by chyroptera over 1 year ago
Posted by chyroptera over 1 year ago

Very interesting. Was at Los Vaqueros yesterday. The Grindelia camporum is just starting to bloom there but I did not notice any leafy galls.

Posted by catchang over 1 year ago

@catchang Some of the galls are bigger than others, but they have been 1-1.5 in size. The larger populations of Grindelias that seem leafier (healthier?) seem to be where I find them--if there just one or two plants, I haven't found any. So far I've only seen them in two places in Alameda County, but there are many more parks and counties to look!

Posted by chyroptera over 1 year ago

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