Disholcaspis plumbella

On Leather Oak in the pigmy forest.

On Leather Oak in the pigmy forest.

On Leather Oak in the pigmy forest.

Disholcaspis plumbella, (Russo). Trail 15 associated with Q. durata Great colors slowly fading. Often at tip end of branch. Photo two shows the exit hole from a previous year's gall. The chamber is now filled with frass.

One of the coolest galls I've seen on scrub oak.

Disholcaspis plumbella, (Russo). Trail 15 associated with Q. durata Great colors slowly fading. Often at tip end of branch. Photo two shows the exit hole from a previous year's gall. The chamber is now filled with frass.

Plant survey in Knoxville Wildlife Area with colleagues from the University of TN.

Gall on oak.

Gall on leather oak. Bright red like a strawberry with yellow dots. (Sierra Azul; Priest Rock Trail)

Found on an overnight backpacking trip in the Bloody Rock area of the Mendocino National Forest, near the Eel River.

Found on Scrub-oak...

Unfortunately I thought I knew the host but turns out Q. berberidifolia and Q. dumosa need some close inspection to separate.

Gall formed by a cynipid wasp on the west coast. Can be greenish with yellow spots or lumps, or wine red with yellow spots or lumps. There is a curved pointed beak opposite the end of attachment. Occurs on blue, scrub, live, and leather oaks in late spring and early summer. Often remains on the oaks for several years. Wasps emerge November and December. - Ron Russo Field Guide to Plant Galls

On Q durata. I have not observed this gall on any other species of Oak.

So imagine a very small wasp lands on your arm and, unbeknownst to you, inserts its ovipositor beneath your skin and inserts a few tiny eggs. The eggs release chemicals that command your body to grow a huge, pustulate turnip on your arm, within which the eggs hatch into little maggots, which in turn replicate asexually for a few generations until some of them turn into adult wasps, at which point they bore out of your arm turnip and fly away. Aren't you happy you're not an oak tree? I believe this was growing on Quercus berberidifolia, but it was also at the Donner cabin site, so it could be some weird cultivar.

So imagine a very small wasp lands on your arm and, unbeknownst to you, inserts its ovipositor beneath your skin and inserts a few tiny eggs. The eggs release chemicals that command your body to grow a huge, pustulate turnip on your arm, within which the eggs hatch into little maggots, which in turn replicate asexually for a few generations until some of them turn into adult wasps, at which point they bore out of your arm turnip and fly away. Aren't you happy you're not an oak tree? I believe this was growing on Quercus berberidifolia, but it was also at the Donner cabin site, so it could be some weird cultivar.