Even Bald-faced Hornets Recycle

Posted on February 26, 2014 by Mary Anne Borge

During the winter, Bald-faced Hornet (Dolichovespula maculata) nests are more visible than they are during the growing season when the woods are dense with leaves.

Bald-faced Hornet Nest in winter

This large nest looks like it is made of paper, and in fact it is. Initially the queen, and later the workers in the colony use their mandibles to scrape up and recycle bits of dead wood, then they mix the wood with their saliva to create the paper mache like substance from which they gradually construct their nest, adding new cells as the colony grows.

Bald-faced Hornet Nest in winter. The bottom has been removed, revealing the cells where larvae develop

These nests are generally not active in winter, except occasionally in the southernmost part of the Bald-faced Hornet’s range. All the colony members die as winter sets in, with the exception of the fertilized queen. She finds a safe, warm place to spend the winter, usually in or under a fallen log, in a hollow tree, or sometimes underground.

In spring, birds take advantage of these abandoned structures and rip away bits of the paper to use as building material in their own nests. If you look at the lower right section of the nest below, it looks like there is some recycled ‘paper’ along with the plant materials that were used in this construction.

Bird’s nest made from plant materials and wasp nest paper

Because paper is used in the construction of the nest, people often think this large football shaped shelter belongs to Paper Wasps. While Paper Wasps use the same materials for constructing their nests, the homes they build for their larvae are much smaller, and somewhat umbrella-shaped, like the one below.

Paper Wasp Nest

Paper Wasp (Polistes carolinus)

Bald-faced Hornets are named for the white markings on their face, and are sometimes called White faced Hornets. They also have white markings on the lower part of their abdomens.

Bald-faced Hornet feeding on nectar. Note the white facial markings that give this species its name, and the pollen on its head.

Does the word ‘hornet’ make you want to reach for a can of insecticide spray? Well, don’t! That’s almost never a good idea.

It may help to know that Bald-faced Hornets are not really hornets! They are wasps, one of the wasp species known as Yellowjackets. Ok, I get that this might not make you feel any more comfortable with them. We’re used to Eastern Yellowjackets relentlessly competing for picnic food, and they can be quite aggressive.

Eastern Yellowjacket (Vespula maculifrons) on Goldenrod

It’s true that if Bald-faced Hornets think you are a threat to their nest, they may sting you, so it’s best to give an active nest a wide berth. As long as you do that, you are unlikely to have an unpleasant encounter with them.

Bald-faced Hornets are actually beneficial in several ways. Like many wasp species, they help to keep the insect population in balance. Bald-faced Hornets feed many types of insects to their developing offspring, and are especially fond of flies and even other Yellowjackets. They can be helpful by harvesting caterpillars for their offspring on a farm or near a vegetable garden – think unwanted Tomato Hornworns.

Bald-faced Hornet nectaring on asters

Adult Bald-faced Hornets feed primarily on nectar or other sweet treats like aphid honeydew. In the process, they provide pollination services to the flowers where they are drinking. And in spite of their size and stingers (in the case of females), Bald-faced Hornets may become a meal for a larger predator.

Bald-faced Hornets can make good neighbors, as long as you give them their space.

References:

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

http://ento.psu.edu/extension/factsheets/baldfaced-hornet

https://nature.mdc.mo.gov/discover-nature/field-guide/bald-faced-hornet

http://naturemappingfoundation.org/natmap/facts/bald-faced_hornet_712.html

http://www.inaturalist.org/taxa/baldfaced_hornet

http://eol.org/pages/239818/overview

http://www.biology.ualberta.ca/bsc/ejournal/bmc_05/84d_maculata.html

http://www.clemson.edu/cafls/departments/esps/factsheets/medvet/baldfaced_hornets_mv15.html

In Praise of Black Walnut Trees

Posted on November 22, 2013 by Mary Anne Borge

If you go for a walk in the woods any time soon, you may still encounter black walnuts or the remains of their hulls on the ground.

Fallen Black Walnuts

The nuts usually remain on the tree until after the leaves fall, reminding me of a Charlie Brown Christmas tree. Then all the nuts fall within a short time of each other. These nuts are sweet tasting and highly nutritious. Studies show that eating them helps prevent cardiovascular disease, diabetes and cancer. Walnuts have as much protein as an equal weight of beef, but they also contain essential fatty acids that are necessary for healthy brain development and function. Any aging brains out there? Eat walnuts!

Black Walnut (Junglans nigra)

Mammals other than humans like them, too: squirrels, mice and voles, for example.

Eastern Gray Squirrels eat and help disperse Walnuts

Red Squirrels also enjoy many tree nuts, including Walnuts

These animals aid in the spread of Walnut trees when they overlook some of the nuts they have hidden away for later use, effectively planting them.

In turn, these animals are food for larger animals, like fox

Red Fox

and raptors.

Red-shouldered Hawks, as well as most other raptors, hunt and eat small mammals

According to Douglas Tallamy in Bringing Nature Home, the leaves of Black Walnut (Juglans nigra) trees and the closely related Butternut (Juglans cinerea) provide food for the caterpillars of over 100 species of moths and butterflies, including Luna Moths and Banded Hairstreaks.

Banded Hairstreak on Butterflyweed. Their caterpillars feed on the leaves of Black Walnut and other woody species

The Walnut Caterpillar specializes on Black Walnut and relatives such as Butternut. This means the leaves of these trees are the only food these caterpillars can eat.

Walnut Caterpillar (Datana integerrima)

Since they are an important source of food for birds, not all caterpillars will see life as an adult butterfly or moth.

Tufted Titmouse

Black Walnut trees have a reputation for not playing well with other plants. That is, many plants won’t grow successfully in close proximity (within the drip-line or reach of the roots) of a Black Walnut. The reason is more complex than shade and competition for water. Black Walnuts contain juglone, which is an anti-fungal chemical. In order to derive nutrients from the soil, the vast majority of plants partner with underground mycorrhizal fungi (think mushroom, not the mold in your shower). Unless the fungi on which the plant depends is resistant to juglone, or the plant doesn’t require this partnership to obtain its nutrition, that plant won’t do well. Of course, some plants and their fungi partners have evolved in exactly this way. Click here for some suggestions from The Mortem Arboretum for plants that can co-habit successfully with Black Walnut trees.

It’s of benefit to Black Walnut trees to produce juglone, since it does reduce competition for resources, and protects the trees from fungal invaders that might do them harm. Juglone also has sedative properties that may aid animals in dormancy. It can even have a calming effect on people.

Black walnut trees contain another compound called ellagic acid in both their nuts and leaves. This compound is thought to help prevent cancer in people who consume the nuts. The ellagic acid in the leaves is effective in removing carcinogenic hydrocarbons from the air, helping to reduce the effects of air pollution.

As if that weren’t enough, Black Walnut’s wood is valuable for furniture and cabinet making, and the nut hulls can be used to make a dye.

Black Walnut with hull partially removed

These are just some of the known benefits of Black Walnut trees. Just imagine what we don’t know yet! No wonder ‘juglans’ is sometimes translated as ‘nut of Jupiter’, or ‘nut of the gods’.

Black Walnut Tree (Juglans nigra)

Resources

Beresford-Kroeger, Diana. Arboretum America: A Philosophy of the Forest. 2003

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

Tallamy, Douglas W. Bringing Nature Home. 2007

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

Butterflies and Moths of North America

Natural History Museum Database of Leipidoptera Hostplants

Nutritious Fall Foliage: What makes leaves so colorful?

Posted on November 8, 2013 by Mary Anne Borge

Red Maple (Acer rubrum)

On Halloween, the Red Maple (Acer rubrum) outside our kitchen window gave up the ghost, so to speak. The leaves on the north side of the tree had been changing colors for weeks, but the rest of the tree remained stubbornly green. Overnight, the entire tree was awash in reds and oranges.

It’s the change in day length (or really night length) and temperature that signals deciduous trees and shrubs that it’s time to get ready for winter. They have to drop their leaves to protect themselves from damage that would be caused due to the heavy weight of winter ice and snow storms. As nights get longer and temperatures drop, these woody plants gradually slow and eventually stop replenishing chlorophyll, the substance that is responsible for the green pigment in their leaves.

Alexauken Wildlife Management Area, West Amwell, New Jersey

But what accounts for the array of colors that are revealed as the chlorophyll gradually disappears? The yellow, orange, red, purple, bronze and browns?

These colors reflect some of the same nutrients that are present in the plant-based foods we eat. Many of these chemicals were present throughout the growing season, but were masked by or blended with the green of the chlorophyll.

American Beech (Fagus grandifolia) Leaves in Spring

American Beech (Fagus grandifolia ) Leaves in Fall

The yellows are carotenoids, mainly xanthophylls, nutrients that help to reduce inflammation, boost the immune system and reduce tumor growth. They are present in yellow summer squash, beets, carrots, corn, peppers, green leafy vegetables, and many others. Xanthophylls help plants to absorb energy from the sun while protecting tissues against the sun’s intense radiation.

Alexauken Wildlife Management Area, West Amwell, New Jersey

Carotenes (another group of carotenoids) are responsible for the orange shades revealed in fall leaves. Beta-carotene is an anti-oxidant, visible in the orange color of foods like winter squash, carrots and sweet potatoes. They assist in photosynthesis, and help protect plant tissues from too much exposure to the sun’s rays.

American Hornbeam (Carpinus caroliniana) or Ironwood

Reds and purples are anthocyanins, nutrients found in foods like blueberries, blackberries, cherries, grapes (and red wine; yay!), purple cabbage, other purple-tinged greens like red leaf lettuce, some kale and swiss chard, as well as many others that show red or purple colors. Anthocyanins are antioxidants, with anti-inflammatory, anti-viral, and anti-cancer properties. Plants may also benefit from anthocyanin’s antioxident effect, and the dark colored pigments help protect from sun damage. They continue to manufacture these chemicals until the leaves fall.

Maple-leaf Viburnum (Viburnum acerifolium)

Brown and tan colors show the presence of tannins. They tend to be bitter or astringent tasting, and as a result discourage browsing by herbivores (plant-eaters) so they may provide some protection to plants. Tannins are found in foods like grapes, wine, tea, and chocolate, though, so you can see that this protection isn’t foolproof.

Spring Lake at Roebling Park, Abbott Marshlands, Hamilton Township, New Jersey

There is overlap and blending of colors based on the mix of chemicals in the leaves. These bright colors may also signal to birds that there is fruit available for consumption.

Yellow-rumped Warbler with Poison Ivy Fruit

These nutrients, along with others that are obtained from the soil, like calcium and potassium, break down and return to the soil as the fallen leaves gradually decompose. During this process, animals may still take advantage of the nutrients. Red-banded Hairstreak caterpillars, for example, feed on fallen leaves, especially those of sumacs, contributing to the process of decomposition, and the cycle of life for the next generation.

Red-Banded Hairstreak

A few days later, and the leaves on our Red Maple have almost all fallen. We’ll watch them gradually break down, nourishing the soil, and the plants and animals that rely on them.

Haul Road at the Trapp Family Lodge, Stowe, Vermont

Resources

http://science.jrank.org/pages/5303/Plant-Pigment-Carotenoids.html

http://www.usna.usda.gov/PhotoGallery/FallFoliage/ScienceFallColor.html

Butterflybush – Are there better alternatives?

Posted on September 11, 2013 by Mary Anne Borge

About a year ago I was asked by the editor of Butterfly Gardener, a publication of the North American Butterfly Association, to take the ‘con’ side in a debate about whether to use Butterflybush. I knew it was invasive, but until I started to research the article, I didn’t realize the extent of its reach.

It’s all about the next generation: The Caterpillars

There’s no denying that Butterflybush (Buddleja davidii), also called Orange Eye Butterflybush, can be a lovely plant. In a sunny location it has attractive flowers, blooms for a long period of time, and may draw a variety of species of adult butterflies for nectaring. What more could a butterfly gardener want? What else is there to know?

What about caterpillars?

Pipevine Swallowtail Caterpillar on Dutchman’s Pipevine (Aristolochia macrophylla)

In Butterflies Through Binoculars, Jeffrey Glassberg says “The most important factor contributing to the decline of butterfly species is habitat loss.” Glassberg also states “For many uncommon butterflies the easiest way to locate colonies is to search for sites where the foodplant is common.” By food plant, he means the plant(s) on which the next generation, the caterpillars, can feed and thrive. Perpetuation of butterfly species requires habitat that will support a butterfly’s full life cycle, not just the adult stage.

Kenn Kaufman, in his Field Guide to Butterflies of North America, states “A butterfly’s most important relationship is with the plants eaten by its caterpillars”. Butterflies of the East Coast: An Observer’s Guide by Rick Cech and Guy Tudor notes “the most important single determinant of butterfly distributions, as well as many other aspects of their lives” are the butterfly’s “host plants”, the food plants that caterpillars need to survive.

None of these sources identify Butterflybush as a food plant for butterfly caterpillars. Does it provide food for the hungry caterpillars of any species of butterflies or moths native to North America? A search of the Natural History Museum’s database of known host plants yields only one species of Lepidoptera present in North America as using Butterflybush as a food plant, the Buddelja Budworm Moth, present only in urban areas of California and thought to be introduced there. So it’s not a known caterpillar food plant. Even if a caterpillar is spotted on Butterflybush, more study would be necessary to see if it gets sufficient nutrition to successfully become an adult.

Isn’t it enough that Butterflybush is a good nectar source?

It would be, except for one thing.

The Orange Eye Butterflybush Plant Fact Sheet from the USDA Natural Resources Conservation Service includes a bright red warning, “Caution: This plant may become invasive.” The USDA lists it as naturalized in 20 states, British Columbia, and Puerto Rico. This means it has escaped from gardens to surrounding natural areas, with the potential to crowd out native vegetation that is essential to wildlife, including butterflies and birds. And is difficult to remove once it has established itself.

According to the USDA, Butterflybush (except for a few sterile cultivars) is prohibited for entry, transport, purchase, sale or propagation in the state of Oregon. It is prohibited from being propagated, released, displayed or sold in New Zealand, is listed as one of the top 20 weeds in Western Europe, and in 2007, the US Fish and Wildlife Service Bayscapes program listed it as a plant that should no longer be used for landscaping. (Soure: The Invasive Buddleja davidii (butterfly bush).(Report), The Botanical Review, September 1, 2009, Tallent-Halsell, Nita G.; Watt, Michael S.)

It’s not that Butterflybush is inherently a bad plant. It is native to China, not North America, Europe or New Zealand. The insects, birds and other residents with which it evolved in China and that depend on it for food there aren’t present in the areas in which it was introduced. So there are no species here that will naturally keep it in check. This is always a potential danger when a species is introduced in an environment in which it is not native, where its food web partners are missing.

A sterile cultivar might be worth a try, but they have a tendency to evolve back into a fertile state over time, so they may become a problem further down the road. Is it worth the risk? (See Developing Sterile Invasives by Ellen Susa )

There are better alternatives

The good news is that there are lots of great alternatives to Butterflybush.

For caterpillar food plants, consider trees and shrubs like Black Cherry (Prunus serotina), Tuliptree (Liriodendron tulipifera), Oaks, Northern Spicebush (Lindera benzoin), blueberries (Vaccinium corymbosum, V. augustifolium), Gray Dogwood (Cornus racemosa), Ninebark (Physocarpus opulifolius), Hoptree (Ptelea trifoliata) and Pipevine (Aristolochia species), and herbaceous perennials including American or Maryland Senna (Senna hebecarpa, S. marilandica), Blue False Indigo (Baptisia australis), violets, milkweeds and asters.

Azure laying eggs (ovipositing) on Ninebark (Physocarpus opulifolius)

Red Admiral Nectaring on Ninebark

For nectar, in addition to the plants listed above, you can’t beat Mountain Mints, Common Buttonbush (Cephalanthus occidentalis),

Indian Skipper and Bumble Bee nectaring on Buttonbush (Cephalanthus occidentalis)

and Coastal Sweetpepperbush (Clethra alnifolia). What thirsty butterfly could resist pink clouds of Joe-Pye-Weed (Eutrochium species),

Eastern Tiger Swallowtails and Peck’s Skippers nectaring on Joe-pye-weed (Eupatoriadelphus species)

bold purple New York Ironweed (Vernonia noveboracensis),

Zabulon Skipper nectaring on New York Ironweed (Vernonia noveboracensis)

Northern Blazing Star (Liatris scariosa),

Monarch on Northern Blazing Star (Liatris scariosa)

Purple Giant Hyssop (Agastache scrofulariifolia), or sunburst yellow coneflowers?

Green-headed Coneflower (Rudbeckia laciniata) with American Copper and Bumble Bee

From late summer through fall, the shimmering yellows of goldenrods

Common Buckeye and Potter Wasp on Goldenrod

and the many bright hues of asters are a prolific source of food for hungry butterflies and native bee species, while hosting many other insects that provide essential food for birds.

Orange Sulphur nectaring on Aster

Listed above and pictured here are just a few of my personal favorites. Good sources of information about plants that will work well in your area include Attracting Native Pollinators by Mader, Shephard, Vaughan, Black and LeBuhn; Bringing Nature Home by Douglas W. Tallamy, the North American Butterfly Association website, and your state or regional native plant society.

Most of us (except in places where prohibited, like Oregon and New Zealand!) are free to choose. Would you like to have a chance to watch butterfly species successfully raise new generations on your property, and protect their habitat in the natural areas near you? Choose well, and you will also have a continuously changing display of colorful blossoms to host adult butterflies from early spring through late fall.

Note: This is adapted from an article that appeared in the Summer 2012 issue of Butterfly Gardener, a publication of the North American Butterfly Association.

The Mist, the Meadow, and a Mystery

Posted on February 23, 2013 by Mary Anne Borge

The weather this winter has been very variable, with warm temperatures and foggy conditions one day, followed by cold, wind and snow the next. On one of the recent warm foggy days, I went for a walk at Bowman’s Hill Wildflower Preserve, just south of New Hope, Pennsylvania. The misty air exaggerated everything – silence, sounds, colors and images.

Fog in the woods

Soft light intensified the bright white and green of the Lumpy Bracket (Trametes gibbosa) mushroom, causing it to jump out and catch my eye.

Lumpy Bracket (Trametes gibbosa)

The changeable weather makes it challenging to adjust to the season, not just for people, but for plants, too. I saw Golden Alexanders (Zizea aurea) in bud, a plant that typically blooms in early May in this area in eastern Pennsylvania. A little scary!

Golden Alexanders (Zizia aurea)

Two White Ash (Fraxinus americana) trees were sentinels on the approach to the meadow…

White Ash (Fraxinus americana) trees at the edge of the meadow

…where the grasses were beaded with water droplets.

Switchgrass (Panicum virgatum)

Indiangrass (Sorghastrum nutans)

There were many signs of life in the meadow. A spider successfully blended in with the dried fruit capsules of Culver’s Root (Veronicastrum virginicum).

Culver’s Root (Veronicastrum virginicum) with spider

Chinese Mantis (Tenodera aridofolia sinensis) egg cases were very common.

Chinese Mantis egg case on Indian-hemp (Apocynum cannabinum) fruit capsules

Much less common was the egg case of a native, the Carolina Mantis (Stagmomantis carolina). I only found one.

Carolina Mantis (Stagmomantis carolina) egg case

The mantises are pretty indiscriminate about where they deposit their egg cases. They are not plant specific, but will use any sturdy structure that’s handy – a shrub, a perennial, even a fence will do. Each egg case, or ootheca, may contain hundreds of eggs. The young will all emerge at the same time in the spring. (Unless they’re eaten by another insect first!)

Goldenrod galls were evidence of insects overwintering. A gall is a growth that is a plant’s reaction to being used, or colonized, by another organism. Galls generally don’t cause any harm to the plant.

Goldenrod Ball Gall

One of the easiest galls to recognize is the goldenrod ball gall, a spherical growth found on the stems of some goldenrods, caused by the goldenrod gall fly (Eurosta solidaginis), a fruit fly. There are many species of goldenrod, but the goldenrod gall fly is very particular about which species it will use; it specializes primarily on Solidago altissima, but Solidago giantea may also be a host. (Solidago altissima goes by many common names: the USDA calls it Canada Goldenrod, but other sources may use Tall or Late Goldenrod. Solidago giantea is Giant Goldenrod according to the USDA, but it is referred to by other sources as Late or Smooth Goldenrod. So confusing! This makes the need for a standard scientific name clear.)

The adult female goldenrod gall fly lays an egg in the leaf bud of the goldenrod before the leaves unfold. After hatching, the larva bores into the stem of the plant, and begins to eat. This stimulates the plant to generate additional nutrients and the gall tissue, a process that takes about three weeks to complete. The gall provides food and shelter for the insect for the remainder of its stay. After spending the winter in a dormant state, called diapause, if the insect is lucky it will pupate in spring and then emerge as an adult from its winter home.

But there are many dangers that could cut the life of the goldenrod gall fly larva short while it takes shelter in the gall. Other insects, including two chalcid wasp species, Eurytoma gigantea and Eurytoma obtusiventris, may eat the insect larva and take possession of the gall. If the goldenrod gall fly larva manages to avoid these and other predators, a Downy Woodpecker or a Chickadee may make it a tasty winter meal.

This Goldenrod Ball Gall has been excavated by a Downy Woodpecker

The goldenrod bunch gall resembles a flower, but it is actually a rosette of leaves caused by the entry of a goldenrod bunch gall midge (Rhopalomyia solidaginis) larva into the stem of its host goldenrod species, Solidago altissima. This stops additional upward growth in the stem of the plant, although leaves will continue to sprout, forming the rosette. Additional growth is through side shoots branching off from the stem below the gall. The presence of this gall actually increases the diversity of other insect species where it is present, by providing additional habitat for them.

Goldenrod Bunch Gall

I found a wonderful, complex, twisted, origami-like structure made in the leaves of Indiangrass (Sorghastrum nutans) that remains a mystery to me.

Mystery shelter

Could it be a winter shelter for a butterfly caterpillar, maybe a Pepper and Salt Skipper? This butterfly is possible, although not common in this area, and its caterpillars spend the winter in rolled grass leaves, including Indiangrass. Maybe some other skipper? Or did a spider make this refuge? If you have any idea who could be hiding inside, let me know!

If you are lucky enough to have custody of a meadow, you may be wondering how to maintain it without killing the critters that live there. To prevent a meadow from evolving into a forest, you will have to mow it. But this will disrupt habitat for the resident insects, birds and mammals. To minimize the damage, try mowing at a height of 12-16 inches, in a mosaic pattern if possible, and don’t mow more than a third of the meadow in a year. For the sake of birds and mammals, mow as late in the winter as you can. These techniques will help preserve life, and increase the diversity of the residents in your meadow.

Chipping Sparrow on Indiangrass

Resources

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

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

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

Special thanks to Beatriz Moisset, who was generous with information about goldenrod galls, including pointing me to some helpful information on Bugguide.net: http://bugguide.net/node/view/324012

I found this paper especially interesting: Host-plant Genotypic Diversity Mediates the Distribution of an Ecosystem Engineer, by Kerri M. Crawford, Gregory M. Crutsinger, and Nathan J. Sanders

The Natural Web

Exploring Nature's Connections

Category Archives: Conservation

Even Bald-faced Hornets Recycle

In Praise of Black Walnut Trees

Nutritious Fall Foliage: What makes leaves so colorful?

Butterflybush – Are there better alternatives?

The Mist, the Meadow, and a Mystery

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