Gall

Willow Pinecone Galls are one of the most unusual galls found in Ohio; I post a BYGL Alert! about them every year. Maybe more than one to spread the gall-joy! The galls are created by the Willow Pinecone Gall Midge to house, nourish, and protect a single fly larva (maggot) located deep within the gall. The literature lists a number of willow hosts; however, I've only ever found them on black willow.

  Let us call this A Case of Gallignostics. Plant galls are defined as abnormal plant growths caused by a gall-maker; the gall-maker being certain insects, mites, fungi, and bacteria. From horned oak gall to bacterial crown gall, from maple bladder galls to cedar-apple rust galls, there are many galls of interest to horticulturists. Relative to all this, Joe Boggs recently got an e-mail from Michael Goldman of the Grange Insurance Audubon Center:

 

  I'm a big fan of the BYGL, and found something here that might be interesting for it.  The pictures I took look like some...

Look closely at the leaves of slippery elm (= red elm) (Ulmus rubra); you may be lucky enough to spot the unusual looking elm cockscomb galls produced by the so-called elm cockscomb aphid, Colopha ulmicola.  Although these galls are commonly mentioned in the literature, I've rarely seen them in southwest Ohio where elm sack galls produced by the aphid, Tetraneura ulmi, are the dominant aphid gall found on slippery elm.

 

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One of my all-time favorite plant galls is the appropriately named Translucent Oak Gall.  The galls are produced by the gall-wasp, Amphibolips nubilipennis (family Cynipidae).  They arise from a leaf vein on the lower leaf surface and measure around 1/2 - 3/4" in diameter.  Their shape and color causes them to strongly resemble tiny, pink balloons or pink grapes hanging beneath the leaves of red, scarlet, and black oaks. 

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While hiking (sweating!) along a forested walking trail near my home over the weekend, I came across several types of oak apple wasp galls on their namesake hosts.  These unusual plant growths can range in size at maturity from 1/2 - 2" in diameter and are named for their resemblance to apples.  The galls are constructed of leaf tissue that has been hijacked by a gall wasp (Family Cynipidae) to surround a single wasp larva located within a seed-like structure positioned at the center of the gall.  The exact species of gall-wasp that is responsible for producing the oak-apple gall can be...

Phomopsis Gall on Hickory. 

An arboretum walk, a mature tree flowering and leafing out, a lovely spring day, a – gall. A bunch of galls, in fact, on this one tree. At first glance, the galls looked like horned-oak or gouty oak galls, round to oblong stem galls that occur on oak. The areas on the stems even looked sort of oak-ish at first, with masses of pollen-bearing male catkins evident. Not an oak, though, as the compound leaves attested. It was a hickory, and the galls, unlike the insect-induced horned oak and gouty oak galls, were caused by a fungus, the Phomopsis  ...

Hickory petiole galls produced by Phylloxera subelliptica (family Phylloxeridae) are appearing on hickory in southwest Ohio.  The single-chambered, ball-like galls range in size from 1/4 - 1/2" in diameter and arise from leaf petioles as well as along leaf midveins.  They may occur singly or in clusters to hang grape-like from their namesake host.  The galls range in color from solid greenish-white to bi-color forms involving splashes of reddish-pink.  Fully mature galls split open at to release the phylloxeran adults through a longitudinal slit.  Spent galls either dry out to...