Shrubby St. Johnswort

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For about eight weeks during the summer, Shrubby St. Johnswort (Hypericum prolificum) is decorated with flowers, like ornaments on a holiday tree in mid-summer.

Shrubby St. Johnswort (Hypericum prolificum)

Each bright yellow blossom has five petals that provide a backdrop to a sphere-shaped burst of stamens, the male reproductive parts of the flowers.  Reaching out for a pollen deposit from the very center of the flowers are their female reproductive parts, called pistils.

Shrubby St. Johnswort (Hypericum prolificum) flower

This gaudy display is attractive to me, but more importantly, it’s a very effective lure for potential pollinators.  Bumble Bees are among the most likely visitors and effective pollinators.  While they climb around the stamens, eating and harvesting pollen from the anthers at their tips, they also pick up quite a bit of pollen on their hairy bodies.  As they forage, pollen on their bodies may be brushed off on the stigma at the tip of a flower’s pistil, setting the wheels in motion for pollination to occur.

Female Bumble Bee (Bombus impatiens) foraging on Shrubby St. Johnswort flowers

Female bees eat pollen themselves, and they also collect pollen to bring back to their nests to feed their larvae.  In the photo below, you can see the ‘bee bread’ this female has collected on her hind legs.  Quite a haul!

Female Bumble Bee (Bombus impatiens) harvesting pollen from Shrubby St. Johnswort flower

Other bees, like Sweat Bees, also visit the flowers for their pollen.

Female Sweat Bee (Lassioglossum species) harvesting pollen from Shrubby St. Johnswort flower

Female Sweat Bee (Lassioglossum species) eating pollen from Shrubby St. Johnswort flower. Notice the pollen on her back leg that she has harvested to take back to provision her nest for her larvae.

Flies are also consumers of pollen.  Flower Flies (also called Syrphid flies or Hover flies) are among those attracted to this pollen banquet.  They may also help with the pollination process, although their bodies are not as hairy as many of the bees.

Flower Fly or Syrphid Fly (Toxomerus geminatus) on Shrubby St. Johnswort flower

This bounty of pollen is so successful in enticing insects for whom pollen is an important part of their diet, primarily bees and flies, that Shrubby St. Johnswort doesn’t expend any energy producing nectar, finding it unnecessary to do so.

If the inadvertent pollination activities of these insects provide the expected payoff, this shrub lives up to the designation ‘prolificum’ in its scientific name, becoming ‘very fruitful’.  Fruit capsules replace the flowers, eventually opening to release their seeds for dispersal by gravity, or by hitching a ride on a passing animal. These dry fruits are visible throughout winter and into the following spring.

Shrubby St. Johnswort (Hypericum prolificum) fruit capsules

Shrubby St. Johnswort is related to the more well-known Common St. Johnswort (Hypericum perforatum), which is used for many medicinal purposes.  Shrubby St. Johnswort shares at least one chemical compound, hypericin, with its more famous relative.  Hypericin has a photosensitizing effect on its consumers, that is, it makes the skin of the animal that eats it especially sensitive to the sun, and exposure to sunlight after consumption results in rashes.  Producing hypericin evolved as an effective deterrent to animals that might otherwise be tempted to eat this plant, including deer.

Shrubby St. Johnswort is a relatively compact deciduous shrub that can grow to a height of about 6.5 feet (2 meters).  It does well in a variety of soils, from dry and rocky to moist, and can tolerate full sun to part shade.  Shrubby St. Johnswort is native in the eastern half of the United States, and in the province of Ontario in Canada.

Shrubby St. Johnswort (Hypericum prolificum)

 

Resources

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

Eastman, John.  The Book of Field and Roadside.  2003.

Hoffmann, David.  Medical Herbalism.  2003.

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

Stearn, William T. Stearn’s Dictionary of Plant Names.  1996

Illinois Wildflowers

USDA NRCS Plants database

Missouri Botanical Garden

 

Love Blueberries? Thank a Native Bee!

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It’s blueberry season in New Jersey!  There are plenty of delicious deep blue orbs ripening for use on cereal, in pancakes, pies, crisps, cobblers, muffins, or just for snacking.  The blue color reflects the presence of anthocyanins, antioxidants with anti-inflammatory, anti-viral, and anti-cancer properties. Blueberries are not only tasty, but good for you.

A Bowl of Blueberries

For anyone who loves blueberries, you should know that some of our native bees are the most effective pollinators of this flavorsome fruit.

Blueberries are the fruit of deciduous shrubs that generally bloom in spring.  Most commercial blueberries in this region are cultivars of native blueberry species, usually Highbush Blueberry (Vaccinium corymbosum).  Lowbush Blueberry (Vaccinium angustifolium) is a species whose fruit is commonly harvested and sold in New England.  If the flowers are pollinated, the fruit ripens in mid to late summer, depending on their growing conditions.

Lowbush Blueberry (Vaccinium angustifolium)

An essential partner in the production of blueberries are the bees that are the primary pollinators for blueberry flowers.  While commercial growers may use Honey Bees to pollinate their crops, there are several species of native bees that are much more efficient blueberry pollinators.

How could that be?  Honey Bees pollinate flowers for a living.  Many are shipped from farm to farm specifically to pollinate crops.  (I think of them as the migrant workers of the insect world.)  How could there be bees that are more efficient pollinators?

Flowers come in all shapes and sizes, and they store and dispense their nectar (if they produce any) and pollen in many different ways.  Blueberry flowers are bell-shaped, with a narrow opening that allows access to the flowers’ nectar from the bottom of the hanging blossom.

Highbush Blueberry (Vaccinium corymbosum) Flowers

Lowbush Blueberry (Vaccinium angustifolium) Flowers

The pollen is most efficiently dispensed from the flowers’ anthers through a process called sonication, or ‘buzz’ pollination.  Buzz pollination is a process of releasing pollen by which the pollinator clings to the flower and vibrates its wing muscles without moving its wings.  This sets up enough of a vibration for the anthers to discharge a dusting of pollen on the flower visitor.  The wing vibration makes a buzzing sound, which gives this technique its name.  (Buzz pollination is the bee equivalent of ventriloquism!.)  Some of the pollen will be carried from flower to flower to enable pollination, while the rest is a pay-off for this service, and will be eaten by the bee and her larvae.  Bees drink nectar, but pollen is also a very important food source for them.

Honey Bees are not capable of buzz pollination, but several families of native bees are, including bumble bees, large carpenter bees, mining (Andrenid) bees, many sweat bees, some mason (Osmia) bees and Melitta bees.  Highbush and Lowbush Blueberry shrubs evolved with these bees who are native to the same region and habitats.  These native bees are able to handle the flowers more quickly and dispense and carry more pollen than the Honey Bees who lack this athletic skill.  Mason bees generally are very swift and efficient pollinators, able to process flowers many times more quickly than Honey Bees.

Mining Bee (Andrenid) visiting Lowbush Blueberry (Vaccinium angustifolium) Flower

Some of the native bees who are able to buzz pollinate specialize on visiting the flowers of blueberries; they and their larvae can only digest pollen from blueberry plants.  This is a great benefit to the blueberries, since these bees spend all of their foraging time visiting blueberry flowers, and there is no risk of pollen being dropped off on the wrong species.  It’s a risk for the bees, however.  If no blueberry flowers are available when the bees are active, the bees have no back-up plan; they could starve.  On the other hand, if blueberry flowers are available, it’s like assembly line processing. The bees know how to handle the flowers very efficiently to get the nectar and pollen they need to survive.

Mason Bee (Osmia) visiting Lowbush Blueberry (Vaccinium angustifolium) Flower

Blueberries are not the only crop that is most efficiently pollinated through sonication.  Cranberries, tomatoes, tomatillos, potatoes, peppers and eggplant are some of the other crops that have a higher rate of pollination when native bees with this skill are available to help pollinate their flowers.

A love of blueberries is not exclusive to people. Many other mammals and birds also enjoy the tasty fruit. Black bears are probably second to humans as consumers of blueberries, but fox, rabbits, raccoons, mice and many more eat their share, too.

Red Fox are among the animals that love blueberries.

Ruffed and Spruce Grouse relish the bounty blueberries provide,

Spruce Grouse

as do many other birds including Bluebirds, Catbirds, Scarlet Tanagers, Tufted Titmice, Veeries, Robins, and Brown Thrashers.

Eastern Bluebirds love blueberries

Veery in Fringtree (Chionanthus virginicus) Veeries are among the many birds who eat blueberries.

Butterflies and moths depend on blueberries, too, but in a completely different way.  Many species use the leaves and flowers as their caterpillar food.  The Natural History Museum’s Database of the World’s Lepidopteran Hostplants (HOSTS) lists 32 species that use Highbush Blueberry as caterpillar food, 42 that use Lowbush Blueberry.

Spring Azure butterfly. Highbush and Lowbush Blueberry shrubs are a caterpillar food plant for Spring Azures.

Saddleback moth caterpillar. Highbush and Lowbush Blueberry shrubs are a caterpillar food plant for Saddlebacks.

Caterpillars are an important part of the diet of many birds and other animals, so feeding caterpillars means that these other species will have the food they need, too.

Female Common Yellowthroat with Caterpillar

Blueberries are great landscape plants.  Not only do they provide food for our many animal neighbors (and us, if we’re quick!), but they are beautiful throughout the seasons, with their spring flowers, summer fruit, fabulous fall color and winter architectural structure and slightly shredding bark.  Why would anyone plant the non-native, invasive Burning Bush (Euonymus alatus) for its brief flash of color, when they could have blueberries instead?

Lowbush Blueberry (Vaccinium angustifolium) with Lichen in Fall

Highbush Blueberry is native primarily in the eastern third of the United States and Canada, but also in Washington state and British Columbia.  It is common in dry to wet woods, in thickets and on stream banks.  It can grow to a height of about 13 feet (4 meters).  Lowbush Blueberry is native from Manitoba to Newfoundland and Labrador provinces in Canada, and south as far as Tennessee and North Carolina (except Kentucky) in the United States. It can be found in dry woods and barrens, where its partnership with mycorrhizal fungi helps it to get the nutrients it needs from the soil.  It is a low growing plant, usually to a maximum height of about 2.5 feet (.75 meters).

The USDA NRCS Plant Database lists 25 species of blueberries that are native in different regions in North America.  Find one that’s native where you live, and add it to your landscape to enjoy its beauty and bounty.

A Bowl of Blueberries

A Bowl of Blueberries

Related Posts

Nutritious Fall Foliage – What Makes Leaves So Colorful?

The Buzz About Shooting Star

Partridge Pea Puzzles

Resources

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

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

Eastman, John.  The Book of Field and Roadside.  2003.

Holm, Heather.  Bees An Identification and Native Plant Forage Guide.  2017.

Mader, Eric; Shepherd, Matthew; Vaughan, Mace; Black, Scott Hoffman; LeBuhn, Gretchen.  Attracting Native Pollinators: Protecting North America’s Bees and Butterflies.  2011.

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.

Wilson, Joseph S.; Carril, Olivia Messinger.  The Bees in Your Backyard. 2016.

Illinois Wildflowers

Natural History Museum’s Database of the World’s Lepidopteran Hostplants – Vaccinium corymbosum

Natural History Museum’s Database of the World’s Lepidopteran Hostplants – Vaccinium angustifolium

 

Trilliums, Flies and Ants

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For a few brief weeks in spring, Painted Trillium (Trillium undulatum) opens for business, the business of surviving as an individual plant and reproducing to ensure the continuation of the species.

Painted Trillium (Trillium undulatum)

Trilliums get their name from their structure.  Their leaves and flower parts are in threes or multiples of three.  Each plant has a whorl of three leaves below a single flower that has three petals, three sepals, six anthers, and a three-celled ovary.  ‘Undulatum’ refers to the wavy edges of the flower petals.

Painted Trillium’s three leaves act like solar panels to gather energy from the sun, enabling this plant to produce the carbohydrates it needs to grow and thrive, and to produce flowers that will enable reproduction if the flowers are pollinated.

Painted Trillium (Trillium undulatum)

Painted Trillium flowers have three bright white petals with paint-splatter-like dark red splotches at their base, bleeding into the petal’s veins.  This color contrast is an advertisement designed to attract potential pollinators to visit the flowers, implying that there is nectar and pollen available for a hungry insect to eat.  Painted Trillium offers these rewards because it needs help from a courier to move its pollen to another plant if it is to successfully reproduce through cross pollination.

Fly investigating Painted Trillium (Trillium undulatum), attracted by the dark red nectar guides

There is not a lot of documentation about the likely pollinators for Painted Trillium, but on more than one occasion, I have seen flies visiting the flowers.  The showy display works!  But the flies’ motivation is not to help with pollination.  They have their own needs to meet, mainly finding food.  They may visit the anthers to eat some nutritious pollen,

Fly harvesting pollen from Painted Trillium (Trillium undulatum)

and follow the colorful guides at the throat of the flower, diving deep to look for nectar.

Fly looking for nectar in a Painted Trillium (Trillium undulatum) flower

While foraging on the flower for food, the fly will likely rub its body or legs against the stigmas at the tips of the flower’s female reproductive parts, depositing pollen she may have brought on her body from a previous visit to a Painted Trillium flower.

Fly foraging on a Painted Trillium (Trillium undulatum) flower, with the underside of its abdomen brushing against the stigmas at the tips of the female reproductive parts of the flower. If this Painted Trillium is lucky, the fly will be depositing pollen picked up from another flower.

Fly foraging on a Painted Trillium (Trillium undulatum) flower, with its legs grasping the stigmas at the tips of the female reproductive parts of the flower.

It will also likely rub against the anthers of this flower, picking up pollen to take with it to deposit on the next Painted Trillium flower it visits.

Fly on a Painted Trillium (Trillium undulatum) flower, with its legs brushing against the anthers, from which pollen is dispensed.

Fly on a Painted Trillium (Trillium undulatum) flower, with the underside of its abdomen brushing against the anthers, hopefully picking up some pollen to take to another flower.

This inadvertent pollen transport is what Painted Trillium is counting on.  It has evolved to attract these unwitting pollination partners, and is willing to pay the energy price to reward them in exchange for their assistance with cross-pollination.

Several Trillium species with dark red flowers have evolved to attract flies as their pollinators.  The dark red flower color is often accompanied by a somewhat rank aroma. Together these features are meant to mimic dead rotting flesh (ok, carrion) or other decomposing matter.  Several fly species seek out this kind of material to lay their eggs.  When the larvae emerge from the eggs, they eat the decaying matter, breaking it down and add the result to the soil layer after it passes through the larva’s body.  These insects help crime scene investigators estimate time of death for a corpse, based on the stage and rate of development of the insect in the decaying body.  Many fly species are attracted to the flowers that use this strategy, only to be disappointed when there is no suitable place to lay their eggs.  At least the flies can console themselves with a pollen snack.

Trillium species that use this deceptive strategy include Red Trillium (Trillium erectum), and Toadshade (Trillium sessile, T. cuneatum).

Red Trillium (Trillium erectum)

Red Trillium has many aliases.  It is also known as Purple Trillium, Wake-robin and Stinking Benjamin, this last name a nod to the flowers’ scent, Wake-robin because it blooms at about the same time Robins returned from their wintering grounds, back when they used to migrate more.

Toadshade gets its name from stories of toads taking refuge under the umbrella-like leaves of the plant.

Toadshade (Trillium cuneatum, T.sessile)

In the photo below, a fly is investigating one of the anthers, the source of the flower’s pollen.

Toadshade with fly

If the flower is successfully pollinated, a fruit develops and ripens later in the summer.  The fruit is a berry that splits open when ripe, making its many seeds available for dispersal.  Each seed has an elaiosome attached, a nutritious food packet whose chemical content mimics that of an insect.  This mechanism has evolved to attract ants to disperse the seeds.  It works because ants are omnivorous; they eat some plant material and enjoy sweet treats such as nectar, but insect protein is an important part of their diet.  The ants are attracted to the seeds because of the elaiosome.  They take the seeds back to their homes, eat the elaiosome, and toss the seed on their compost heap, effectively planting the seed in a fertile, protected location.  This evolutionary strategy, known as myrmecochory, is shared by many spring blooming wildflowers.

If you need proof that other insects are important ant food, you’ll find some evidence in the photo below.  I watched while this ant worked tirelessly to drag to its home the moth it’s grasping, working its way across the trail, letting no obstacles like sticks, leaves or rocks deter it from its mission!

Insects are an important source of food for ants. This ant worked tirelessly to drag the moth back to its home.

The elaiosome strategy works in much the same way that fleshy fruits attract birds and other animals to eat their fruits and ‘disperse’ the seeds complete with fertilizer after the seeds pass through the animal’s digestive system, a trait used by many plants that bloom later in the season.

Trilliums typically grow in moist woods.  Painted Trillium is native from Ontario and Quebec south through northern New Jersey and much of Pennsylvania, from there south through the Appalachian mountains to northern Georgia and South Carolina.  It is also present in parts of Michigan.  Red Trillium’s range is a bit broader, from Ontario, Quebec and Michigan, south through northern Alabama, Georgia and South Carolina, with some presence in Indiana and Illinois.  Trillium sessile can be found from western New York state west to Illinois, Missouri and western Kansas, south from Oklahoma to north Carolina.  Trillium cuneatum is native in Pennsylvania, Maryland and Virginia, west to southern Illinois and south from Mississippi to Georgia.

These lovely Trilliums depend on flies and ants for their continued survival.

Painted Trillium (Trillium undulatum)

Related Posts

A Carpet of Spring Beauty, Woven by … Ants!

Resources 

Gracie, Carol.  Spring Wildflowers of the Northeast. 2012.

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

Marshall, Stephen A.  Flies The Natural History and Diversity of Diptera.  2012.

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

Michigan Natural Features Inventory, Trillium undulatum. Willdenow. 2004.

USDA NRCS Plants Database

https://plants.usda.gov/core/profile?symbol=TRUN

https://plants.usda.gov/core/profile?symbol=TRER3

https://plants.usda.gov/core/profile?symbol=TRSE2

https://plants.usda.gov/core/profile?symbol=TRCU

USDA Forest Service Plant of the Week, Painted Trillium (Trillium undulatum), Larry Stritch

 

 

A Dazzling Green Beetle: Six-spotted Tiger Beetle

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For the past few weeks, I’ve been seeing dazzling green Six-spotted Tiger Beetles (Cicindela sexguttata) along wooded trails, and even on the paths through my shade garden.  I think of these brightly colored beetles as one of the harbingers of spring. They are most commonly seen from spring through early summer in openings in or next to wooded areas.

Six-spotted Tiger Beetle (Cicindela sexguttata)

This eye-catching beetle is named for the spots on its elytra (outer wings), although the number of spots is variable; an individual may have more or less than six spots.

Six-spotted Tiger Beetle (Cicindela sexguttata) with 6 spots

Six-spotted Tiger Beetle (Cicindela sexguttata) with 8 spots

Six-spotted Tiger Beetle (Cicindela sexguttata) with 8 spots

Sometimes called the Six-spotted Green Tiger Beetle, its coloration is most often a vivid metallic emerald green, but in some individuals it may take on a bluish hue.

Six-spotted Tiger Beetle (Cicindela sexguttata) with bluish coloration

Their large eyes, long legs and sickle-shaped mandibles are characteristic of the tiger beetles.

Six-spotted Tiger Beetle (Cicindela sexguttata). The large eyes, long legs and white sickle-shaped mandibles crossed in front of its head are characteristic of tiger beetles.

When I see a Six-spotted Tiger Beetle, it’s often because it spotted me first.  Their color lets them blend in when they are resting on foliage.  I see them when they dash ahead of me along a trail, stopping after a few feet, always keeping some distance between us unless I approach very slowly and carefully.  The beetles’ large eyes give them a broad field of view, the better to see their prey and avoid predators, which include robber flies, dragonflies, other insects, birds and small mammals.

Six-spotted Tiger Beetles are carnivores.  They eat various insects and other arthropods, such as spiders.  The beetles capture their prey with their large, white, ferocious-looking mandibles.

Six-spotted Tiger Beetle (Cicindela sexguttata) with prey

Even as larva, tiger beetles feed themselves by hunting for their own insect meals. Female tiger beetles dig holes in the ground to lay their eggs, one egg per hole, then the hole is covered with soil.  When the larvae hatch, they enlarge their underground tunnel and stay just below the ground level opening, waiting for a hapless insect to walk by.  With lightening-like speed, the larva juts part way out of its home, grabs its victim with its mandibles, drags it back inside its home tunnel, sprays it with digestive enzymes to liquefy it, filters out any solid bits and drinks the rest.

Adult male Six-spotted Tiger Beetles use their mandibles for an additional purpose.  Even after a pair finishes mating, the male may use his mandibles to retain his hold on the female, preventing any other male from attempting to mate with her.

Six-spotted Tiger Beetles (Cicindela sexguttata). Note that the male, who is the beetle on top, is retaining a hold on the female with his mandibles.

It takes about a year for the beetles to complete their metamorphosis.  Adults may live for a few years, often spending the winter in the same underground tunnel it used in its larval and pupal stages.

The Six-spotted Tiger Beetle is found from southeastern Canada to the Dakotas, south from eastern Texas to Florida. Look for these bright green beetles on a wooded trail near you!

Six-spotted Tiger Beetle (Cicindela sexguttata)

Resources

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

Evans, Arthur V.  Beetles of Eastern North America.  2014.

Evans, Arthur V.  Field Guide to Insects and Spiders of North America.  2008.

Marshall, Stephen A. Insects Their Natural History and Diversity. 2006.

AnimalSake

University of Connecticut Home & Garden Education Center

Minnesota Seasons.com

Indiana Department of Natural Resources

 

Hackberry, Butterflies and Birds

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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,

Mockingbird

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)

Resources

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

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Illinois Wildflowers
http://www.illinoiswildflowers.info/trees/plants/hackberry.html
http://www.illinoiswildflowers.info/trees/tables/table153.html

USDA NRCS Plant Database
https://plants.usda.gov/core/profile?symbol=CEOC
https://plants.usda.gov/plantguide/pdf/pg_ceoc.pdf

USDA US Forest Service

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