Cottony rosette stem galls on Wyoming big sagebrush
Here are photographs of a rosette gall that I'm trying to identify, all growing on Wyoming big sagebrush (Artemisia tridentata subs. wyomingensis at the Crooked River National Grassland in Madras, Oregon. Galls are between 1 and 4 cm in diameter and are composed of dozens of thin, pointed bracts coated with fine white hairs. There are thousands at the location.
I'm assuming they are some sort of Rhopalomyia (Cecidomiidae), but I can't find a good match in iNaturalist, BugGuide, or on any of the hundreds of web pages and books that document the various galls on sagebrush. Similar galls have also been observed by @ddubois2 on Artemisia cana in Montana (https://www.inaturalist.org/observations/45283788#activity_comment_4818259) and by @serpophaga on Artemisia dracunculus in California (https://www.inaturalist.org/observations/8919705, https://www.inaturalist.org/observations/8919707).
It seems improbable that something so striking is not yet described. If anyone has ideas on what it might be, I'd be grateful for any leads.
Observations
Photos / Sounds
What
Leafy Bud Gall Midge (Rhopalomyia anthoides)Observer
colinpurringtonDescription
Cottony rosette gall on Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis).
Photos / Sounds
What
Genus RhopalomyiaObserver
colinpurringtonDescription
Cottony rosette gall on Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis).
Photos / Sounds
What
Genus RhopalomyiaObserver
colinpurringtonDescription
Cottony rosette galls on Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis).
Photos / Sounds
What
Genus RhopalomyiaObserver
colinpurringtonDescription
Cottony rosette gall on Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis). Use of "cottony rosette gall" is not to suggest that's the common name; just descriptive.
Photos / Sounds
What
Genus RhopalomyiaObserver
colinpurringtonDescription
Cottony rosette gall on Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis).
Photos / Sounds
What
Insects (Class Insecta)Observer
colinpurringtonDescription
Orange larva inside a rosette gall on Wyoming big sagebrush. Not sure whether this is the galler (Rhopalomyia?), an inquiline, or a parasitoid. Second pic is larva inside another gall from the same plant — many of the galls in area have these larvae.
Here's one of the galls:
Photos / Sounds
What
Insects (Class Insecta)Observer
colinpurringtonDescription
White larva inside a rosette gall on Wyoming big sagebrush. Not sure whether this is the galler (Rhopalomyia?), an inquiline, or a parasitoid. Second pic is larva inside another gall from the same plant.
Here's one of the galls:
Comments
Hello I'm trying to tag you in my post on inaturalist photos. Please look for me. I'm trying to find out if this is an invasive praying mantis. Thanks. I'm having trouble posting and tagging lol. yvette123
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