Oak trees with balls

What’s in a name?

Updated: Oct. 17

Shh … nobody tell the monkey ball trees.

Their dense, sticky fruit used to feed woolly mammoths 10,000-some years ago. The giant creatures are gone now, of course, but the trees don’t know that — and who among us would want to break their arboreal hearts?

So the trees continue each fall to drop their rubbery, green, brain-shaped fruits, assuming woolly mammoths or giant ground sloths will devour and digest them, spreading their seeds across the land and helping the trees expand their timber empire, said Joe Stavish, community education coordinator at Tree Pittsburgh.

Growing up in Canonsburg, Cindy Toth remembers that “as children, we played with monkey balls and threw them in the woods. My dad put them in the basement and said they kept bugs away.”

Thinking back on the “unusual” trees inspired her to turn to The Incline’s Peculiar Pittsburgh series — where readers submit questions and we turn up answers (and often even more questions). She asked:

What’s up with the monkey balls?

“That sounds like a “Seinfeld” bit: ‘What’s the deal with monkey balls,’” Stavish said.

In the life of a tree, 10,000 years isn’t very long, and evolutionarily, the trees haven’t figured out yet that the fruits they spent months growing now plunge the ground to be smashed by cars, thrown by kids, tucked into basements for spider control, used as Halloween decorations, or simply left to rot.

The tree is officially named the maclura pomifera, and also goes by osage orange (that’s oh-sage, not aw-sage), hedge apple, horse apple, bow wood, yellow wood, or monkey brain tree. But many of its nicknames are confusing, because it’s not an orange or an apple tree, Stavish said.

“It’s a tree that has many common names,” Stavish said. “I don’t think anybody knows why the monkey ball name came about.”

Maybe the name is some reference to monkey genitalia, he said, which are sometimes colorful, but the hypothesis can’t be proven. So the name “monkey ball” isn’t the scientific name, but it’s a Pittsburgh phrase, so in this article, we’re going to continue to refer to it as any yinzer would.

The monkey ball.

Courtesy of Joe Stavish, Tree Pittsburgh

From dinner to bows to fence posts

The fruits — the monkey balls, if you will — weigh 1 to 5 pounds and are generally about the size of a baseball but sometimes can be as big as a football. Only female trees produce monkey balls, a collection of flowers known as a “multiple fruit,” explained Bonnie Isaac, collection manager of botany at Carnegie Museum of Natural History.

The green fruits are basically a ball of latex, and they’re not edible to humans, Stavish said, adding that “if you ever cut one open when they’re fresh, they’re white sticky glue. There’s no other trees that produce a fruit like that.”

When they fall to the ground around early October, they now decompose and turn to mush.

But the trees date back nearly 13,000 years, even before the Ice Age, and at that point, its fruit served as breakfast, lunch, and dinner for woolly mammoths in the central United States.

Mammoths, apparently, didn’t seem to have discerning palates. The gigantic mammals swallowed the fruit whole, rather than chewing up the seeds, meaning their waste perfectly preserved the seeds, allowing the trees to sprout in new places.

The trees, it seems, never learned that their metaphorical dining room was empty.

“It’s a tree that doesn’t really know that the mammoths have gone extinct,” Stavish said.

After mammoths, humans found new uses for the trees. The Osage Nation, a Native American tribe, used the trees’ orange-colored, rot-resistant wood to make bows.

“It was a very strong wood, and it was very flexible, which you need for a bow,” Stavish explained.

Eventually, Lewis and Clark found out about the trees when they traveled into St. Louis and sent some specimens to Thomas Jefferson, Isaac said.

Lining the edge of a Westmoreland County farm, this monkey ball tree has just dropped its fruits.

Courtesy of Joyce Skena

As agricultural development began in the 1800s, farmers coveted the trees’ thorny exteriors for fence posts and planted the trees in a line to create a natural fence keeping animals in their fields and other animals out, Stavish said. Farmers planted millions, spreading the tree from its native land of Texas, Arkansas, and Oklahoma across the country to places like Pennsylvania.

On the plains, the trees also provided a shield to protect crops from strong winds, added Brian Wolyniak, extension educator of urban and community forestry for the Allegheny County Penn State Extension.

Once barbed wire was invented, tree-lined fences fell out of popularity, though you can still find some around the Pittsburgh area that clearly once lined the perimeter of a property.

Now, the trees, which range from shrub size to 40-feet tall, are seen as a messy tree since they don’t grow into a nice shape, Stavish said.

But despite its ugly duckling exterior, he said, “It’s a wonderful tree and it has a unique history. … It’s a great tree that we should still have in our urban forest.”

How are the trees used today?

Today’s wildlife don’t eat monkey balls.

“Deer, elk, and moose don’t like the taste of the latex,” Stavish said. Plus, the fruit can be a choking hazard for cows, Wolyniak said.

At the end of the winter, though, animals sometimes get desperate for food. In those bleak months when everything else is gone, local critters, such as squirrels, will pick the seeds out of the mush, Stavish said.

“The tree was really evolved for those extinct animals,” he said.

Brains — er, monkey balls.

Courtesy of Joe Stavish, Tree Pittsburgh

As for humans, they collect the fruits and put them in their basements to deter spiders and insects. It’s not scientifically proven, but the oils in the fruit may act as a natural insect repellant — that is, until the fruit rots and attracts fruit flies, Stavish said.

“I have a row of them in my front yard, and spiders will build their webs right over them, but there’s still people who will swear by it,” Isaac said.

The fruits also make excellent Halloween decorations, Stavish said, given their creepy look.

But not to rain — er rot — on your parade, Isaac cautions: “They’ll rot just like everything else eventually.”

Before they start decomposing, kids enjoy rolling them down hills — or throwing them, as our question-asker remembers.

“They’re definitely a weapon of war for the neighborhood children,” Stavish said.

The orangish wood, which Isaac describes as “absolutely gorgeous,” still makes excellent bows, tool handles, and even furniture.

Homewood-based Urban Tree LLC rescues trees that are being cut down and turns them into furniture — that includes monkey ball trees.

The hard but flexible wood makes a strong exterior-grade material for things like outdoor playgrounds, benches, or chairs, which the company has built at local schools and Phipps Conservatory, Urban Tree partner Jason Boone said.

“It’s not a very common find for material. … It doesn’t typically get very big and it doesn’t grow very straight to make lumber out of it,” Boone said. “It is pretty nice when you can finish it out.”

The shorter stumps, pictured here at Phipps Conservatory, are made from monkey ball wood.

Courtesy of Jason Boone, Urban Tree

Find a monkey ball tree near you

Want to see one in real life?

Hunt for them atop Mt. Washington, near Construction Junction in Point Breeze North, or by the Blue Slide Park playground in Squirrel Hill.

“They’re definitely not a common tree,” Stavish said. “Some of them are definitely survivors of the old fences.”

A freeze-dried monkey ball.

Courtesy of Bonnie Isaac, Carnegie Museum of Natural History

Though the plants quickly take root, few people plant them these days.

“It’s kind of an old-fashioned kind of thing,” Isaac said. “I’ve not seen a lot of recent platings. The really old farms — that’s where you see them.”

People do ask about them, though, so Isaac keeps some “spectacular” freeze-dried monkey balls in the museum’s collection, though they’re not currently on public view.

“I have a few people always asking if they can see the freeze-dried monkey balls,” she said.

Though the trees didn’t originate here, they’ve certainly become a part of the common lexicon and natural landscape.

“While it’s not necessarily native, it’s kind of taken hold,” Wolyniak said. “It’s not something we eat. It’s not something animals eat. It’s an interesting anomaly in a sense that they’re still around.”

Ask us your questions about Pittsburgh and our region:

Editor’s Note: You’ve asked us so many great questions about local trees that we answered them here: Monkey balls, banana apples, and buckeyes: Answering all your Pittsburgh tree questions


Have you ever seen round extrusions on oak trees that seem to hang like fruit? Oak galls, also called oak apples, are a common phenomenon produced by the oak trees’ reaction to wasps that lay their eggs inside of the oak bark. Oak galls are high in tannic acid and have been used traditionally as medicine by many cultures around the world; they are also a source of dye and tanning material. Oak galls contain unique and potent properties that are just beginning to be studied by mainstream scientists for a host of useful applications.


Oak galls come in many sizes, shapes and colors but are all products of the oak trees’ reaction to the larvae of certain wasps known as gall wasps. These larvae cause the oak tree to manufacture cells and substances that produce the gall and in turn the wasp larvae use the gall as both food and shelter. The galls usually do not harm the oak; however, the gall formation is a defensive measure by the oak tree and therefore contains strong natural astringent compounds such as tannic acid. In fact, according to Botanical.com, oak galls are the most astringent vegetable compound in the world.

Medicinal Uses

Oak galls are used in Chinese medicine as a bitter warm remedy called moshizi, used for dysentery, ulcers and hemorrhoids among other things, according to Subhuti Dharmananda, PhD in a paper entitled “Gallnuts and the Uses of Tannins in Chinese Medicine.” American Indians used poultices of ground gall nuts on sores, cuts and burns, according to Christopher Hobbs in “A Field Guide to Western Medicinal Plants and Herbs.” Botanical.com recommends oak galls used as a tincture in cases of diarrhea, cholera and gonorrhea.

Other Uses

The high tannic acid content of oak galls also makes them a good source of tanning and dyeing material. Many tribal groups employed oak galls for a variety of decorative and curing uses including pottery, leatherworking and basketry.


Recently there has been an interest in using oak galls as a source of natural pesticide, as that is its original function and intent by the oak tree itself. In a 2009 article in the journal Parasitology Research, researchers at the University of Mysore in India found that an extract from oak galls had larvicidal activity against Anopheles stephensi, a type of mosquito that is responsible for the spread of malaria in urban areas.


Oak galls are easy to identify and are found worldwide in many different varieties. Collecting oak galls neither harms the oak tree nor hurts the gall wasp larvae once they have hatched. There are many possible uses for oak galls as an easily accessible source of tannic acid while out in the wild, and the possibilities for using oak galls in creative ways have yet to be exhausted.

Oak trees have a lot of gall – ‘oak apple gall,’ that is

Q: My oak tree looks like it is making fruit the size of ping-pong balls. Now I know that they make acorns, so they couldn’t possibly make fruit, right? What are these round plum-looking fruits hanging from my oak tree? When you cut them in half they are hollow inside.

Q: My oak tree looks like it is making fruit the size of ping-pong balls. Now I know that they make acorns, so they couldn’t possibly make fruit, right? What are these round plum-looking fruits hanging from my oak tree? When you cut them in half they are hollow inside.
A: You are right; oaks make hard acorns not plum-type fruit. What you are seeing are galls. Galls occur on many woody plants. They can be caused by different organisms – fungi, nematodes or mites – but insects such as wasps are the primary cause. Your perfectly round ping-pong-sized galls were probably caused by a gall wasp or, as entomologists call them, the cynipid wasp. Most galls are small, but some can be as large as 2-inches in diameter. When the gall wasp lays an egg on developing plant tissue, it begins to change. The irritated plant tissue quickly surrounds the egg or immature insect and protects and provides food for the gall-maker until it matures. If you see a gall, inspect it closely for a pin-sized hole; this is the exit hole where the developed wasp left the gall.
The galls you are seeing on your tree are often called “oak apple galls,” which is a common name for galls shaped like small apples. Dr. Eileen Buss of the University of Florida entomology department says that “the galls probably occurred after the first spring leaf expansion on oak trees, but are not likely to be damaging to trees. Many gall-maker species are active (mating, laying eggs) from just before the trees put on new growth to early shoot and leaf expansion in late March to mid-April.” Since they are not damaging to the trees, there is no reason to treat the tree or trim away the galls.
There are many different types of galls. “If kids need to do a class biology project, collecting different galls on oaks can be fun and interesting,” Buss suggests.
– – –
Q: Can live oak leaves around my shrubs harm them? One neighbor advised me that these leaves were bad for shrubs. A landscaper I consulted recently suggested removing all the leaves from around my shrubs because some were dying. He suggested that they were preventing water from getting to my plants. I always thought leaves made good mulch.
A: Leaves make great mulch, but you can overdo it. If your leaves are piled too thickly over the roots of plants, they can prevent water from reaching the root zone. I am all for using your fallen leaves in your landscape. It helps to recycle nutrients on site instead of having them picked up by the yard waste truck or, worse, blowing them into the street where they can clog up the storm drains and add extra nutrients into creeks.
Whole leaves, especially oak leaves, can take years to break down. To use your oak leaves as mulch, it is best to grind them to a one-fourth- to one-half-inch pieces so they will break down quickly. Grind your leaves with a chipper, shredder machine or run over them with a lawn mower. Apply the mulch in a 2- to 3-inch layer. At this thickness, you will suppress weeds, help the soil hold moisture and add to the organic matter of your soil.
Wendy Wilber is an extension agent with UF/IFAS. E-mail her at [email protected]

Oak Galls: “Curiouser and Curiouser!”

Colorful Galls are quick to catch the attention of curious gardeners. All photos by Bill Seaman.

Published October 30, 2013 By Bill Seaman

Like Lewis Carroll’s character Alice, I too “quite forgot how to speak good English” when first researching the strange world of plant galls. The more I learned, the curiouser and curiouser I became! Instead of a lesson in horticulture, entomology, and plant physiology, learning the ins and outs of galls is akin to learning how to deliver Texas Tall Tales. Both have fascinating stories, but the part of the brain that houses logic keeps nagging, “Great story, but it can’t be true, can it?” This is the story gardeners need to know about oak gall.

In the simplest terms, galls are plant tissue growths resulting from exposure to minute amounts of hormone-like chemicals produced by the gall makers. The gall makers can be fungi, bacteria, nematodes, or mites — but insects are the primary culprits. Galls can occur on roots, flowers, bark or buds, but the galls on leaves and twigs are the most noticeable.

Mealy Oak Gall is commonly found on Live Oaks. The woody gall structure may remain attached to the twigs for years.

Texas gardeners are probably most familiar with the galls that appear on their oak trees. On live oaks, it is usually Mealy Oak Galls — those tan, jawbreaker-sized orbs that persist on the outer twigs long after the acorns drop. When they finally drop, they are woody, hard on bare feet, and on close inspection, have a single exit hole where the adult gall maker has gnawed its way out of its home.

Now this is where the truth begins to sound like a tale. With Mealy Oak Gall, the gall maker is a wasp. Entomologists call it a wasp, but gardeners associate wasps with yellow jackets and hornets. To us, wasp implies stingers. For gardeners, it might be more appropriate to think fruit fly, as the cynipid wasp is similar in size and sting to the fruit fly. That is a roundabout way of stating there is no sting.

Mother wasp finds an appropriate live oak twig to which she attaches her egg, and the chemicals on the egg induce the oak to grow a home for the soon-to-hatch grub. That is how Mealy Oak Galls are formed. The grub dines on the interior tissue of the gall until it matures and chews its way through the outer shell to be free to mate, lay more eggs — in the case of the females — and die. The gall structure is now vacant and can persist on the twig for a number of years as a curiosity, or drop to the ground, to the bane of fussy gardeners.

While there are as many different galls in oaks as there are cynipid wasps, the life cycles are similar. However, the life cycles can be much more complex than stated here. Some even include both a sexual and an asexual phase that I will leave to the entomologists to explain.

For most galls on oak trees, the insect is a species of cynipid wasp. And, strangely enough, each species of wasp is associated with a specific species of oak tree. Oak Apple Gall is commonly found on both Texas red oaks and Shumard red oaks. Unlike the Mealy Oak Gall, this lime-sized gall looks to be fragile, with a thin, translucent outer cover. It retains its spring-green color into summer, when it fades to a light brown. When the skin is peeled away, an interior structure of cotton-candy-like fibers is revealed.

Oak Plum Galls can be difficult to spot in the canopies of red oaks, but are easily seen when they drop to the lawns below.

Oak Plum Gall is also found on red oaks. These grape-sized galls are colored maroon and cream, and are easier spotted on the lawn as they begin to drop, than nestled in with the clusters of acorns in the trees. This gall could be mistaken for a tropical fruit, and if cut in half, reveals a dark red center with a single larva in the center.

Galls from a post oak clutter the ground as they detach from leaves and twigs in time to be covered with fall’s leaf litter.

I have found that the best way to manage oak galls is by pouring a large glass of ice tea, adding a squeeze of lemon and a sprig of mint, and finding a good book to read. While it is true that some galls are harmful, oak galls are not. The resources surrendered by the tree are negligible. Applying insecticides to manage the adult population at the time eggs are laid would require precise timing and would have a negative effect on beneficial insects. If you are concerned about the aesthetics, take some comfort in knowing that the gall makers tend to be cyclical. Some years bring heavy infestations while others bring none.

When you do find galls in your garden, take time to inspect them closely. You too, will become curiouser and curiouser.

Posted by Mr. Bill Seaman Insects | Diseases | Galls | Neil Sperry

About the author

Mr. Bill Seaman

Mr. Seaman is a sixth generation Texan, degreed horticulturist, and member of the certified arborist team at Arborilogical Services, “The Experts Your Trees Deserve.”®

(Picture: DeAgostini/Getty Images)

We’ve previously ranted about Etsy allowing people to sell unhealthy, benefit-free, potentially dangerous products for vaginal ‘health’.

There were the detox balls. The tightening sticks. Yoni oil.

Mum urges parents to trust their instincts after baby’s acid reflux was actually cancer

But we reckon this one takes the cake – purely because it sounds so truly absurd that we can’t believe Etsy is allowing the product to be listed.

Surely, selling wasp nests to insert into the vagina is too far, even for chill, ‘sell whatever!’ brand Etsy.

Alas, no.

A seller called HeritageHealthShop was able to get away with selling oak galls (also known as oak apples) for vaginal use. They’ve since removed the listing, but not before gynaecologist and general queen of calling out nonsense vagina products, Dr Jen Gunter, spotted it.

(Picture: Etsy)

Oak galls, if you didn’t know, are balls of bark and the excretions of wasps. They host wasp larva, and grow when a gall wasp punctures an oak tree and deposits their larva into the hole.

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This causes the tree to secrete tannic and gallic acids, creating a little spherical thing called a gall nut, oak gall, or oak apple. They have a little hole where the baby wasp pokes its way through to escape.

HeritageHealthShop recommended applying oak galls ‘topically’ (by which she means putting them inside your vagina) or orally.

(Picture: Getty)

‘Some women take manjakani to improve their sex life,’ the listing read. ‘Some say it can tighten the vagina.’

The listing went on to suggest that people could insert oak galls into their vagina after childbirth, take it orally to ‘restore the elasticity of the uterine wall’, apply it to the vagina to heal episiotomy scars, or boil the galls to turn them into a ‘feminine wash’.

Like other dangerous vagina-targeted products on etsy, the listing is essentially recommending using drying agents to tighten the vagina – which, as Dr Jen points out, is a terrible idea.

‘Drying the vaginal mucosa increases the risk of abrasions during sex (not good) and destroys the protective mucous layer (not good),’ writes Jen.

(Picture: Minerva Freire)

‘It could also wreak havoc with the good bacteria.

‘This is a dangerous practice with real potential to harm.’

We’ve said it before, but just to repeat it with feeling: the vagina is a magical self-cleaning thing that pretty much takes care of itself, through a healthy pH balance and bacteria.

Your vagina really does not need to be messed with.

(Picture: Ella Byworth for Metro.co.uk)

It’s not supposed to be dry and insanely tight. It’s supposed to be wet. That’s how the vagina keeps itself clean and healthy.

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You do not need to shove anything up there to change your vagina, whether to clean it, tighten it, or dry it out. And if you are concerned about vaginal issues, the best port of call is a medical professional, not dodgy products sold by untrustworthy people on the internet.

It’s worth noting that while HeritageHealthShop may have removed their listing following backlash, there are still other people selling oak galls for vaginal purposes on Etsy and through other websites.

(Picture: Etsy)

A store called Indojuara markets oak apples as a way to ‘tighten vagina’, deal with urinary infections, and get rid of ‘bad smells’.*

*A note on this, your vagina isn’t supposed to be odourless. But if it does smell particularly offensive, again, talk to a doctor.

Stay woke. Do not buy these products. Do not trust products marketed towards tightening the vagina, even if they’re all natural and seem safe (just because something is natural doesn’t mean you should stick it inside yourself).

Let your vagina do its thing, and if you have any issues go to your doctor. Not to Etsy.

We reached out to Etsy for comment, who told us the below:

Etsy’s response:

‘We are currently investigating this issue, but due to our privacy policy, we cannot comment on a specific shop or seller.

‘When sellers open a shop or list an item on Etsy, they agree to follow our site policies and terms, as well as local and national laws.

‘However, it is important to understand that Etsy is not a curated or juried marketplace. We evaluate items on a case by case basis as we become aware of them.

‘Due to the nature of our platform, it is possible that a prohibited item may appear for sale on the site before our enforcement teams have a chance to remove it. Members are welcome to report these items to us. We have a timely review process for all reports.’

MORE: Someone is sewing vaginas on to Beanie Babies and we don’t understand why


MORE: Woman issues glorious warning about using Original Source’s mint shower gel around your vagina

MORE: Is your vaginal discharge normal?

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Enter the Oak Gall. Provider of tannic acid for centuries past and up through today. The Oak Gall is the “gall” part of “iron gall ink.” So, what is an oak gall? What does it look like? How do I obtain oak galls? Do oak galls have other names they get called? Do all galls have the same amount of tannic acid in them? All good questions.

Oak galls grow on oak trees. I realize that sounds rather obvious. Sometimes though the objects name is misleading so I wanted to be clear about that with you. The oak tree is any of 207 trees or shrubs in the genus Quercus and is in the beech family. Quercus is the Latin for “oak tree” unsurprisingly.

So where to oak trees grow? Oaks grow in many different places and climates. In the USA the oak in some form is prevalent throughout the country. You can buy books on tree identification that will show you the geographical range of various kinds of trees including oak trees. You can also visit this website and get that information for free.

The oak gall is just one of many kinds of galls. A gall is a plants reaction to infection creating a growth to battle that infection. Many plants produce galls. And no, not all galls look alike or are useful for the purposes of making ink. Here is a lovely article discussing all sorts of galls. For our purposes we want the galls created by insects laying their eggs in the leaf buds. Number six in the linked article shows some California “oak apples”.

Yes, oak galls do have different names. A few of the names I have run across are “oak apples” and “oak marbles,” and “gall nuts” even though they are not a nut of any kind nor an apple of any kind. Sometimes in the pre-17th century recipes we simply see them called “galls”.

How do I obtain oak galls? You can purchase them and you can go pick them off the tree or the ground if you find them there. Of course your friends can pick them off the tree for you and give them to you as presents also. Picking oak galls does not harm the oak tree.

What do oak galls look like? This wikipedia article, yes, I know, actually shows a very good assortment of various oak galls. It is actually supposed to be a discussion of one kind of insect that causes oak galls and is heavy on showing the oak galls. It also points to a truth of collecting oak galls for yourself. To get the insect caused leaf galls we are after you first need to have the insects that create them. If your city sprays insecticides to get rid of mosquitoes (and considering the diseases mosquitoes can give you that can be a very smart thing for them to do,) they might be killing off the insects that create oak galls.

I have a collection of galls that I keep both to make ink with and as a display to help people identify galls when they see them.

Oak gall attached to tree branch.

This one fell from the tree I happened to be next to when I was at the park.

A closer look

You can see that the other leaves are healthy which in my experience is typical. This gall is still a bit green but is also drying out to the beige color you usually see on this kind of gall.

A closer view of the gall

Galls are attached to the tree via a stem just like leaves are. It makes sense that they would be.

This gall is from Oklahoma. I have galls from Indiana that look very much the same but have dried out.

Detached dried out gall

These galls are typical of red and white oak varieties. You may have noticed the hole prominently displayed in the picture. That hole is where the insect larvae ate its way out after hatching. Generally speaking galls with these holes are better for our use. Of course sometimes we are going to pick galls without the holes in them. I generally prefer to put the galls I harvested in the freezer in a ziploc container for a week before bringing them back out. This kills any insects that might be in there.

So what are the properties of this kind of oak gall? Well they are fragile, have a papery outer layer and are mostly filled with air and some fluff that contains most of the tannic acid. You can easily crumble these in your hand.

Outside focus

Inside focus

You can see that there is some stringy fluffy bits in there. Let’s get a better look at that.

A separate gall showing the “empty” insides of the gall

The white fluff is connective tissue inside the gall. No reason to get rid of it.

With the tannic acid bundle

I don’t know the technical term for the brown bundle so I call it a bundle. It contains most of the tannic acid in the gall. This one fell out.

Giving you an idea of how much of this kind of gall is actually hallow.

This is roughly how the gall might look if you open it up.

Some size measurement for you.

These are typical galls in size and coloration. Hopefully this helps you if you go out to harvest them yourself. Keep in mind that not all galls are the same.

Twig or branch galls

These are also oak galls. As their name implies they are grows in the twig or branch. They are not very useful for our purposes of making ink. Yes they have tannic acid in them but extracting that out is not a very efficient process. Avoid these galls as they are not going to work well for you.

If you happen to live around live oaks you can get oak galls from them as well. For those who don’t know the live oak is a broad leafed evergreen oak. They don’t lose their leaves like other trees do but they have deciduous leaves unlike the “needles” from coniferous trees such as pines.

The galls from live oaks look entirely different from the galls above.

Live Oak Galls

Live oak galls are smaller and can be a dark to light brown coloration. They are mostly smooth and are dense and hard in consistency. It takes a mortar and pestle, hammer or other smashing implement to break these galls up. I’ve used these galls to make ink with varied results.

If you pick these galls from the tree they contain an acceptable amount of tannic acid in my experience. They are very good for making inks. If you pick these galls up from the ground I have found they leach out their tannic acid very easily to rain and other environmental factors. So picking them up from the ground generally means they will be of lower quality. Just make sure you know what you are getting yourself into and adjust accordingly.

In period and today there is a gall that is considered best.

The Aleppo Oak Gall.

Aleppo Oak Galls

These are small dense, very hard galls. In period and today they are considered the premium type of oak gall. They come from the Aleppo Oak (Quercus infectoria) that is found in the greater Syrian region that covers in part, Syria, Turkey, Iraq, Jordan and Israel.

Aleppo Galls with ruler

Aleppo galls are my preferred gall to make inks with. I generally purchase them from John Neal Bookseller.

Oak galls all have varying levels of tannic acid in them. Typically speaking the aleppo gall content is 65 – 75% tannic acid. Galls from Europe and Britain content is typically 55 – 65% tannic acid. Galls from North America are typically 45 – 55% tannic acid. So make sure you note that when you are making your inks. Sometimes you need to do some math to adjust the amount of galls you need from the recipe depending on what kind of galls the recipe calls for and what kind of galls you actually have.

I hope this informational field guide to oak galls is useful to you.

Horned Oak Gall

ENTFACT-457: Horned Oak Gall | Download PDF

By Lee Townsend, Extension Entomologist and
Daniel Potter, Horticultural Entomologist
University of Kentucky College of Agriculture

Fig. 1 Horned oak galls

Horned oak galls are unsightly, golf ball-size woody growths on oak twigs caused by a tiny wasp (Callirhytis comigera). The name refers to the characteristic horns that protrude from the surface of the mature galls.

Lightly infested pin oaks can live for many years without apparent harm but outbreak infestations can disfigure trees causing extensive branch dieback and even tree death. The clusters of dried out galls, which are especially noticeable after autumn leaf fall, remain aesthetically disfiguring for years after the wasps have emerged and abandoned them. The gouty oak gall, which is similar but lacks the horns, is produced by the wasp C. quercuspunctata. The complex life cycle of these wasps thwarts control efforts.

Life cycle

Large numbers of female wasps emerge from the mature woody galls in late March through mid-April. Each wasp uses a horn as its escape tunnel, chewing an exit hole through the end. Those females place tiny eggs into swelling leaf buds.

Fig. 2 Female gall wasp placing eggs in bud for leaf gall generation
Fig. 3 Leaf gall with emergence hole of wasp

Each leaf gall, which resembles a tiny, inconspicuous blister on the underside of leaves along mid- or lateral vein, contains a white grub-like larva. Those grubs mature into male and female wasps that exit the leaf galls from late May through early June. After mating, females insert eggs in a spiral arrangement around 1- or 2-year old twigs to start the twig gall generation.

Fig. 4 Slight swellings of an
11-month old twig gall.

Twig galls appear as slight swellings about 10 months after egg hatch. They, too, contain small, white larvae. Irregular tissue growth continues and individual swellings combine to form large, irregular woody galls with individual chambers for each developing larva.

Galls increase in size for about 24 months and may house as many as 160 developing wasps. The hollow horns begin to project from galls that are about 2 years old and ultimately serve as escape tunnels. Galls harden and dry after their residents leave and the horns break off. The stem gall generation takes about 33 months from egg hatch to adult emergence. These females move to leaf buds to lay eggs for the leaf gall generation.

Consecutive generations of horned oak gall wasps alternate between developing in small blister-like leaf galls and large, communal, woody twig galls.

No clear management options

Management approaches for the horned oak gall on landscape pin and willow oaks continue to be evaluated but no easy solution has been found.

Canopy sprays in early spring to kill the wasps before they lay eggs in the swelling buds, or sprays in late spring to kill wasps emerging from the leaf galls may provide partial control. Spraying tall trees is impractical in most settings and also kills natural enemies that help keep other pests, such as scale insects, in check. Trunk injections of systemic neonicotinoid insecticides have not proven effective for reducing numbers of leaf galls.

Some professional arborists report that injecting trees with bidrin (a Restricted Use Pesticide) in spring for four consecutive years is suppressing horned oak gall infestations. That approach, which targets the seemingly more vulnerable leaf gall stage, has not yet been scientifically evaluated.

Success is difficult to evaluate because dead twig galls will remain for several years. Infested trees have twig galls in several stages of development, maturation of which takes almost 3 years. Therefore, a single insecticide application does not end an infestation.

If a few woody galls are noticed, it pays to promptly remove them if they can be reached with a pole pruner. However, this is not practical in mature tall trees. Beneficial insects, including several species of parasitic wasps, help to suppress horned oak gall populations on many trees. Individual trees vary in resistance or susceptibility; often some are heavily infested while others nearby are nearly gall-free. The basis for such resistance is unknown.


  • Eliason EA and DA Potter. 2000. Biology of Callirhytis cornigera (Hymenoptera: Cynipidae) and the arthropod community inhabiting its galls. Environ Ent 29: 551-559
  • Eliason EA and DA Potter. 2000. Impact of whole-canopy and systemic insecticidal treatments on Callirhytis cornigera (Hymenoptera: Cynipidae) and associated parasitoids on pin oak. J Econ Ent 93: 165-171.
  • Eliason, EA and DA Potter. 2001. Biology and management of the horned oak gall wasp on pin oak. J Arboriculture 27: 92-100.

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.


Images: University of Kentucky College of Agriculture

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