Hackberry, Butterflies and Birds

Common Hackberry (Celtis occidentalis) is a tree whose ridged, warty bark makes it easy to recognize in any season.  It may be easiest to spot in winter, since there are fewer leaves to distract from Hackberry’s distinctive outerwear.

Common Hackberry (Celtis occidentalis)

Look for Hackberry on a winter day that’s a little warmer than normal, and you might be rewarded with a glimpse of one of the butterflies that are among Hackberry’s known associates, the Mourning Cloak and the Question Mark.

Mourning Cloak butterfly

Question Mark butterfly. It is named for the white markings on its wing.

Both of these butterflies survive the winter as adults, spending most of the time sheltering in dry accommodations such as under loose bark, in a woodpile, or in a crevice or hole in a tree.  The butterflies are able to produce an anti-freeze-like substance that keeps them from succumbing to the winter cold.  They are mostly inactive during the winter; they rarely eat and don’t reproduce.  But they may venture out on a warmish winter day to look for a snack of minerals from rotting fruit, dung, sap or mud puddles.  When you are a butterfly that wakes up from a winter nap in northern latitudes, you have to have a flexible diet.  Not many flowers are blooming to offer nectar during the cold winter months.

While these butterflies may be found anywhere in the woods, in the warmer months when reproduction is on their mind, they are known to associate with Hackberry trees because they are one of the species whose leaves the caterpillars of both these butterflies can eat.  In addition to Hackberries, Mourning Cloak caterpillars use the leaves of a variety of trees, including willows, elms, birch, cottonwoods and aspen.  Question Mark caterpillars can also eat elm tree and nettle leaves.

Question Mark caterpillar on Hackberry leaves

In the spring and summer months, you may see additional butterflies whose caterpillars specialize on Hackberry leaves.  These species depend solely on Hackberries for their survival.  They include the curious looking and aptly named American Snout, the Tawny Emperor, and Hackberry Emperor.

American Snout butterfly drinking nectar from Short-toothed Mountain Mint (Pycnanthemum muticum)

The American Snout drinks nectar in addition to seeking out minerals.  Its long ‘nose’ is thought to have evolved to look like the stem of a leaf, which together with the cryptic coloration of its wings helps this butterfly to hide in plain sight, disguised as a dead leaf.

Tawny Emperor

Hackberry Emperor

Because Tawny and Hackberry Emperors rarely nectar, you are most likely to encounter them in or near wooded areas where their caterpillar food is present.  Their diet of minerals from mud, sap, and rotting materials such as fruit and dung is similar to that of the Mourning Cloak and Question Mark.  Hackberry Emperors also find human sweat to be a good nutritional source.  It is the species of butterfly I have most often seen landing on people to get a quick snack!

Hackberry Emperor getting minerals from soil and rocks.

Hackberry Emperor getting minerals from the sweat on someone’s shirt!

Hackberry Emperor getting minerals from the hood of a car. Is it the paint or the dirt?

Not every caterpillar will live to become an adult butterfly, since there are many predators to elude first.  The Hackberry Emperor caterpillar in the photo below has fallen victim to a parasitic wasp. Her larva will develop inside the caterpillar, consuming its insides until the wasp is mature enough to emerge.  As you might expect, the caterpillar is unlikely to survive.

Hackberry Emperor caterpillar, with a predatory wasp.

Several moth species including the IO Moth, and White-marked and Banded Tussock Moths also use Hackberries, among other woody species, as food for their caterpillars.

White-marked Tussock Moth

Banded Tussock Moth

The round growths on the leaves in the photo below are galls called Hackberry Nipple Galls.  They are caused by a type of true bug in a group called psyllids, or less appealingly, jumping plant lice.  The insects develop inside the galls and emerge when they mature.

Common Hackberry with ripening fruit and Hackberry Nipple Galls, caused by Pachypsylla celtidismamma.

Many of these insects are a potential bounty of food for birds.  I watched the young Tufted Titmouse below and its nest mates forage for food and play among the branches of a mature Hackberry.

Tufted Titmouse in Hackberry

Hackberry’s somewhat inconspicuous flowers are pollinated by the wind, blooming at the same time that the leaves are beginning to emerge.  Hackberries are monoecious; they have some flowers with just male reproductive parts, others with just female flowers, with both types of flowers on the same trees.  In the photo below, both male and female flowers are present.  The female flowers have two stigma-tipped styles that are spread in a ‘v’ shape projecting from the flower. (They look like forceps, or they also remind me of the arcade games where you have to use a similar looking tool to retrieve a toy from a glass enclosure.)  The male flowers have five or six anther-tipped stamens that barely project beyond the enclosing sepals.  A tree may even have some flowers with both male and female parts.  Pollen is carried by the wind from the anthers and deposited on the stigmas.

Common Hackberry (Celtis occidentalis) flowers. The female flowers have 2 styles spread in a ‘v’ shape. The male flowers each have 5-6 dark-colored anthers.

If the flowers are pollinated, a fruit called a drupe is produced.  A drupe is a fleshy fruit that has a stony enclosure around the seed inside, like a peach.  The fruit ripens in fall, but may persist into winter. Birds as diverse as Mockingbirds,


Pileated Woodpeckers,

Pileated Woodpecker

and Wood Ducks eat Hackberry fruit.

A pair of Wood Ducks

Raccoons and squirrels are among the small mammals who eat the fruit.

A raccoon peaking out from its home.

Common Hackberry’s natural habitat includes wooded floodplains and hillsides, and can grow to a height of about 115 feet (35 meters).  It is native in Manitoba, Ontario and Quebec provinces in Canada and most of the United States, from New Hampshire to Montana in the north, south through Utah, New Mexico and east to Florida, except Louisiana, although it is less common in the southern part of its range.   It is also often used as a street tree.

There is a related species, Sugarberry (C. laevigata) that is native in the southern half of the United States and in the western states.  Dwarf Hackberry (Celtis pumila) is native in Ontario, Michigan, and from New Jersey west to Kansas, and south from Texas to Florida.  The butterflies that specialize on Hackberries use these species, too!

Common Hackberry (Celtis occidentalis)


Allen, Thomas J.; Brock, Jim P.; Glassberg, Jeffrey. Caterpillars in the Field and Garden. 2005.

Cech, Rick; Tudor, Guy.  Butterflies of the East Coast.  2005.

Eastman, John.  The Book of Forest and Thicket.  1992.

Eaton, Eric R.; Kauffman, Ken.  Kaufman Field Guide to Insects of North America.  2007.

Eiseman, Charley; Charney, Noah.  Tracks & Sign of Insects and Other Invertebrates.  2010.

Martin, Alexander C.;  Zim, Herbert S.; Nelson, Arnold L.  American Wildlife & Plants A Guide to Wildlife Food Habits.  1951.

Rhoads, Ann Fowler; Block, Timothy A.  The Plants of Pennsylvania.  2007

Tallamy, Douglas W.  Bringing Nature Home.  2007

Wagner, David L.;  Caterpillars of Eastern North America, 2005.

Illinois Wildflowers

USDA NRCS Plant Database

USDA US Forest Service

Oregon State University College of Agricultural Sciences Department of Horticulture Landscape Plants




45 thoughts on “Hackberry, Butterflies and Birds

  1. Thank you so much for the great information. I have one of these trees in my backyard, but wasn’t able to identify it. I am a birder and also have a butterfly garden, so having this information helps me to know that I have another resource for them!

  2. Pingback: Plant Awareness Disparity – The Greenhouse Blog

  3. Beautiful photo and text. I have several mature wild Hackberry trees. However I’ve never seen any of these pretty moths, nor fruit on them. They are however affected terribly by the galls, and the leaves turn yellow and are not very attractive. ☹️🥲

  4. Lovely! I planted a Dwarf Hackberry about 16 years ago. Shortly thereafter I saw my first Hackberry butterflies and then nipple galls and then birds eating the bugs of the galls and fruit from the tree. It’s so rewarding to see how quickly wildlife finds the food that I’ve planted. Great post!

  5. Thanks for this post! I am an employee at a Land Trust in Wisconsin and will be providing environmental education to groups. Very useful information citing two of my favorite things: trees and butterflies! Thank you! I’m anxious to read more of your blog!

  6. Saw the hackberry once and was amazed; never had seen anything like it. As I recall the bark was corky and compressed a little. Very interesting small tree.
    Thanks for article and pictures.

  7. I would suspect that since Hackberry trees are found in Mississippi near the Mississippi River that they would be found in Louisiana also, maybe they are just not being reported!

    • If you zoom in on the map in the link using the slider on the left side of the map, you will see county level data. This info tells an interesting story. Celtis occidentalis is much less common in the southern tier of states than it is in the north. It is found in only a few counties in Louisiana’s neighboring states of Mississippi and Texas. https://plants.usda.gov/core/profile?symbol=CEOC
      Of course, it is always possible that there may be some individuals that have not been reported.
      The good news is that the butterflies (and birds!) also use C. laevigata, which is more common than C. occidentalis in the southern states, including most counties of Louisiana, and the states in the western US, where C. occidentalis is not found. https://plants.usda.gov/core/profile?symbol=CELA

  8. Once again you have opened my eyes to the wonders of a tree I thought I knew. I really enjoyed the photos; especially the tussock moth caterpillars. I will be on the lookout as this wonderful, new season opens. Thank you so much for your work.

  9. Wonderful post! Thank you! Would you happen to know if these butterfly species have the same relationship with Celtis laevigata? That’s the more common one here in Georgia.

  10. Great article! Love those Hackberries. We’ve planted them where we live and in the preserves around our area! Thanks, Mary Anne!

  11. Thanks for this Mary Anne!

    About a month ago, I was looking into additional Lep foodplants for our property and did some reading on Hackberry. I was familiar with it as a foodplant for Snout & both emperors but didn’t realize all the critters that benefit from the fruit. I quickly ordered a few saplings for this spring but I’m left wondering why this isn’t a more popular tree for planting in our local preserves (NJ & PA). Hopefully more people will come to see the benefits of this species.

    • It seems like it’s the kind of tree that sneaks up on you – that’s why I like seeing it in winter. I posted this in a few Facebook groups, and people are responding with their sightings of it, and the fact that they planted it. Around the New Hope – Lambertville area, you can see it on the Lambertville Nature Trail, at Bowman’s Hill Wildflower Preserve, and in the parking lot at the Weidel’s in New Hope!

  12. This is really interesting, so well explained. What fabulous photos. We are planting more hackberries at the Preserve, so timely too!
    Thanks for again giving me more to look for when I play outside.


Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.