Circling back to this many years later! This is an interesting find for sure. Any chance the galls or residents were saved?

Moved from ID Request.

With help from Charley, I contacted Ron Russo and this is what he had to say:

"The picture of the wasp does look like a cynipid wasp. However, there is nothing listed for Hawthorne (I assume this came from Washington State). The positioning of the larval chambers is quite similar to those of both cynipid wasps and cecidomyiid midges. Gagne's book on Gall Feeding Midges of North America does not list any similar gall on hawthorne.

All of this said, this could be a new species. The wasps you found are not necessarily the causative agents as many cynipid wasps are parasites. It would take considerable study to figure this one out.

I would like to see the actual gall along with specific information on when and where it was collected.

I am planning on extensive collecting in the area as we have relocated to Belligham, WA. and expect to find many new species. I will be looking at hawthorne carefully." (~Ron Russo)

If it ever stops raining here today, I am going to go look for more of these on the Hawthorn. I'll "document" it a little better and take more photos. The one thing I will say, though, is that this Hawthorn is in our front yard and I frequent the area quite often. This twig with the gall growing off the tip was on the side closest to where I pass by pretty often... so if it ever was orange and spore-covered, it must have been hidden behind the leaves (while they were still there), because I never saw anything strange before. But in the warmer months when the foliage is "bushier", I guess I could have missed it or passed it off as a berry or something.

Would cutting this "gall" open help at all?

I will go out on a limb here to suggest this may be the "gall" (perhaps "canker" would be a better term) of Cedar-Quince Rust, a fungus. My exploration of this idea follows below; please regard it as a suggestion and not an ID.

A Google search for "hawthorn twig gall" led to several references to Cedar-Quince Rust fungus (Gymnosporangium clavipes), which alternates between cedar (Juniperus) and hawthorn (Crataegus) - and sometimes Quince (Chaenomeles), hence the common name. The Plant & Pest Diagnostic Lab at Purdue University webpage states "on the hawthorn, this fungus causes distortion of fruit, twigs, and buds. Fruits become shrunken and often die; twigs become enlarged and woody. Pinkish-orange tubes ["aecia", spore-bearing fruiting structures], about the size of a pencil lead, protrude from affected fruits and twigs and shed orange spores that are splashed or blown back to the juniper, completing the life cycle of this rust fungus." A particularly nice photo of a fresh specimen on hawthorn appears on the 6 July 2006 entry of the Niche blog by Wayne Hughes and Glenn Galau (scroll way down to near the bottom of the page). Note the orange stubs (aecia) protruding from the round body of the gall, which is formed at the tip of the hawthorn twig (like Mandy's).

Judging by the growth of lichens on Mandy's gall and its overall weathered appearance, I think it is several years old. Thus it likely looks different now than when it was young and fresh (which is typically the form appearing in guidebooks and on websites). In general form, size, and placement, it resembles the cedar-quince gall in the Niche photo (which is consistent with the Purdue description), allowing for the effect of weathering. I wonder if the subtle brown dots on the surface of Mandy's gall might be aecial scars (where the aecia used to be when the gall was fresh) and if the insect holes might be secondary utilizations.

Again, this is an exploration of an alternate idea in face of the lack of an obvious insect explanation.

Does it look like the Hawthorn rust gall? see http://www.ppdl.purdue.edu/PPDL/weeklypics/4-23-07.html