pollinator – Discover-Nature

American Asters

As we enter early autumn, it is late in the growing season for the central United States, and many insect species are still actively looking for pollen and nectar as they get ready for winter. Migrating birds and species that overwinter here are also seeking daily meals. Fall flowering plant species are much fewer in number than summer blooming species, but include varieties of American asters, Symphyotrichum spp.; goldenrod, Solidago spp.; black-eyed Susans, Rudbeckia spp.; coneflower, Echinacea spp.; sedum, Sedum spp.; and anise hyssop, Agastache spp.

^{American Aster by Andrew McKinlay, Aug 2013; Anise hyssop by Steve Guttman, Oct 2011; Black-eyed Susan by Jodi Grundig, Aug 2009; Coneflower by Bonnie Leer, Jul 2008; Goldenrod by Cathy Baird, Aug 2013; Sedum by Eleanor Martin, Jul 2009}

In this blog, we take a look at American asters, which make up a genus of over 100 species of perennial plants, all of which are native to North America. Asters like full or partial sun and reach heights of between one and six feet. They display a variety of colors from white to blue to purple. They do best in wet soils. Asters are often grown in pots or used in borders, as well as being found in a variety of wild habitats including forests, savannas, prairies, and wetlands.

^{American painted lady on Pacific aster by TJ Gehling, Oct 2023; Gulf fritillary on white aster by Vicki DeLoach, Ot 2012; Leaf cutter bee, Megachile spp, on New England aster, by GreenRavenPhotography, Sep 2016; Metallic green bee on white aster by Jacqui Trump, Oct 2021; Pecks skipper, Polites peckius, on smooth blue aster, Symphyotrichum laeve, by Tom Potterfield, Sep 2016}

These asters are an excellent source of nectar and pollen sought by both long-tongued and short-tongued bees, butterflies, wasps, and beetles. All parts of the plant are edible, although some species may contain mild toxins, making the animal eating it ill. Leaves and stems are eaten by grouse, turkey, chipmunks, mice, and deer. The abundant seeds are available long after most other flower seeds have been consumed or buried. Large quantities of seeds are eaten by migrating bird species including dark-eyed junco, Junco hyemalis; indigo bunting, Passerina cyanea; American tree sparrow, Spizelloides arborea; and American goldfinch, Spinus tristis.

^{American goldfinch, Spinus tristis, by F Delventhal, Jul 2022; American tree sparrow, Spizelloides arborea, by Tom Benson, Nov 2018; Dark-eyed junco, Junco hyemalis, by Stan Lupo, Mat 2020; Indigo bunting, Passerina cyanea, by Mitchell McConnell, Apr 2013}

Asters are sometimes referred to as a keystone species. Keystone species can be either plants or animals that are essential to maintaining the health and functions of the entire ecosystem to which they belong. The introduction or loss of a keystone species may significantly affect an entire ecosystem in either positive or negative ways. Populations of other organisms may be altered, habitat changes can be observed, and biodiversity can rapidly change. American asters, along with the other late blooming flower species, are an important food source late in the growing season for maintaining a healthy population of pollinators, migrating birds, and over-wintering wildlife.

To learn more about seasonal changes and how our native species are adapted to handle these conditions, consider a visit to the Jurica-Suchy Nature Museum or a nature center near you.

Greene Valley Trail

As the heat abated a little bit, we decided to take a hike at the DuPage County Greene Valley Forest Preserve in Naperville, Illinois, this past weekend. On the east side, in the central part of the preserve, a 2.25 mile trail loops from the south parking lot to the Southern DuPage County Regional Trail and the Valley Trail. Trails are well-marked, wide limestone paths, with plenty of room for walkers and bicycles.

We found a pleasant, open vista that was great for birdwatchers and prairie enthusiasts alike. The Valley Trail runs alongside the east branch of the DuPage River, which makes it attractive to bird species, although there is no view of the river for hikers. While it was an overcast day making bird identification difficult, we were able to observe those seen below:

^{Birds pictured above in clockwise order: Northern cardinal, Cardinalis cardinalis, by Mshake, Getty Images; Red-winged blackbird, Agelaius phoeniceus, by Robert Jakubowski, Pexels; Song sparrow, Melospiza melodia, by BrianEKushner, Getty Images; Common yellowthroat, Geothlypis trichas, by BrianEKushner, Getty Images; Field sparrow, Spizella pusilla, by Mr Jamsey, Getty Images Signature; Gray catbird, Dumetella carolinensis, by SKHoward, Getty Images Signature}

Vegetation varies greatly, providing good protection for many of the small mammals plus lots of perches for birds. Many plant varieties could be seen and identified without leaving the trails, including those pictured below.

Black raspberry, Rubus occidentalis; Edible in season
Climbing prairie rose, Rosa setigera; Pollinator species for bees
Common milkweed, Asclepias syriaca; Pollinator species supporting more than 450 species of insects
Cup plant, Silphium perfoliatum; Leaf wraps around the stem forming a water holding cup
Eastern Black Walnut, Juglans nigra; It is allelopathic, releasing chemicals from its roots that may give the tree some advantage over its nearest competitors for food and nutrients
Elderberry, Sambucus sp.; Sambucus is Greek for an ancient wind instrument sounding as a whistle
Grey headed coneflower, Ratibida pinnata; Perennial attractive to Butterflies & birds
Hemp dogbane, Apocynum cannabinum; All parts of the plant are toxic, possibly fatal
Joe Pye weed, Eutrochium sp; Considered medicinal by early American cultures
Northern red oak, Quercus rubra; Acorns need a minimum 3-month exposure to near freezing temperatures to germinate
Sumac, Rhus sp.; Prized as a spice from the cashew & mango tree families
Virginia creeper, Parthenocissus quinquefolia; Flowering vine in the grape family
Grey poplar, Populus x canescens; Cross between white poplar and Aspen
Wild bergamot, Monarda fistulosa; Considered medicinal in use as a tea for colds

^{Scroll through pictures above using the left & right arrows}

The area supported plenty of small mammals such as rabbit, shrew, deer, coyote, and both gray and fox squirrels. We saw lots of pollinators including bees, moths, butterflies, and dragonflies. Greene Valley Forest Preserve offers a wide range of hiking trails, a scenic overlook, camping and picnicking facilities, a model airplane field, and many events, including night sky observations throughout the year. Consider catching some of the amazing sights in natural areas near you.

^{Fauna pictured above in clockwise order: Coyote, Canis latrans, by Esteban Arango, pexels; Galls on grape leaves; White-tailed deer, Odocoileus virginianus, by Stefonlinton, Getty Images Signature; White cabbage butterfly, Pieris rapae, by Bejan Adrian, Pexels; Shrew by CreativeNature_nl, Getty Images; Eastern cottontail, Sylvilagus floridanus, by Brian Forsyth, Pexels}

Butterflies

I recently visited The Butterfly Place in Westford, Massachusetts. It was quite nice to walk through and learn about the various species and habits of these beautiful and lively insects.

Clockwise from upper left, all pictures by Don Arnold: Brown Clipper butterfly, Parthenos sylvia; Giant swallowtail butterfly, Papilio thoas; Julia butterfly, Dryas julia; Monarch butterfly, Danaus plexippus; Malachite butterfly, Siproeta stelenes

Butterflies come in a variety of colors and patterns providing camouflage to hide from potential predators, identifying an individual to potential mates, and/or allowing an insect to absorb heat needed for daily activities. The colors we see can come from colored pigments that reflect light of a specific color or from structural pigments that take on different colors depending on the angle and intensity of reflected light. Structural pigments produce blues, whites, and colors with a metallic sheen. Genes control which pigments appear in each part of their wings to create the multitude of patterns. Variations in just a few genes may determine that a pattern in one species is slightly different in size, shape, or color in another species, or completely different in a third species.

Blue morpho, Morpho peleides, with brown & white pattern vs same colors and slightly different pattern on Owl butterfly, Caligo eurilochus

Butterflies eat by sipping sweet nectar from a variety of flowers. Their tongue, called a proboscis, forms a hollow straw that restricts them to a liquid diet. When not eating, you can observe the proboscis curled up in front of their mouth. When uncurled, it forms a long tube, able to reach deep into a flower to the base where nectar is stored. Watch the video below as this monarch inserts its proboscis into the base of the lantana as it feeds. Many butterflies enjoy juice from fruit, especially as it starts to decompose to a softer, more liquid-like stage.

Rice paper butterfly, Idea leuconoe, probing for nectar

Puddling is another feeding activity where butterflies take in liquid from puddles, wet gravel, sweat, and scat. These are all sources for minerals and salts needed for egg development. Females may find their own puddling sources, but males also engage in this activity, passing along a complex package of sperm, minerals, salt, and other nutrients to females during mating.

Clockwise from upper left, all pictures by Don Arnold: Piano key butterfly, Heliconius melpomene; Rice paper butterfly, Idea leuconoe; Sara butterfly, Heliconius sara; Scarlet swallowtail butterfly, Papilio rumanzovia; Zebra longwing butterfly, Heliconius Charitonia

Butterfly houses are interesting and fun places to observe many of these species and their behaviors up close. We can provide for our native butterflies by learning which plants host caterpillars and which plants provide nectar for adults. Select these plants for your garden, or place potted plants on an outside porch during warmer months. You can provide additional habitat for butterflies and other small insects by mowing less frequently, limiting the use of pesticides in your yard, and leaving small brush piles in your garden.

Carnivorous Plants

Plants and insects have myriad relationships to one another. Some are mutually beneficial, as when plants offer nectar to feed insects which in turn pollinate the plants. Other relationships only benefit the insects when they feed on leaves, stems, and roots. For carnivorous plants, preying on insects to fulfill their need for nitrogen and other nutrients benefits only the plants.

^{Venus flytrap, Dionaea muscipula by Len Worthington, Aug, 2016}

Pitcher plants are carnivorous, living in bogs and fens found in warm weather areas. In North America, most species are found along the southeastern coastal states from Texas to West Virginia. Bogs are depressions filled with rain or melted snow, while fens are similar but get their water from surface or groundwater. Both types of wetlands are low in oxygen and nitrogen, very acidic, and often quite cold. These characteristics slow down the rate of decay in the vegetation of the wetland, further reducing the availability of nitrogen which is a vital component of chlorophyll, the compound used by plants, along with water, carbon dioxide, and energy, to photosynthesize sugar for food.

^{Tracy’s sundew, Drocera tracyi by Matthew Paulson, May 2022; Venus flytrap, Dionaea muscipula by Judy Gallagher, Jun 2022; White-topped pitcher plant, Sarracenia leucophylla, showing downward hairs by Aaron Carlson, Sep 2013}

Carnivorous plants use several strategies to attract and trap insects. Pitfall traps have slippery faced leaves forming a funnel with a pool of digestive enzymes waiting at the bottom. Downward facing hairs on the leaves make it harder for insects to climb out. Some plants use an opposite strategy and cover their leaf surfaces with a sticky secretion, trapping any insects that land on them. Still others have a leaf-like structure made of two halves that snap together when an insect lands on an inner surface, trapping the insect inside. In both of the last two instances, digestive enzymes are then released to cover, kill, and break down the insect body for absorption by the plant.

^{White-topped pitcher plant, Sarracenia leucophylla, traps separated from flowers by NC Orchid, Apr 2016}

^{Two-spotted bumblebee, Bombus bimaculatus by Judy Gallagher, Jun 2022}

Carnivorous plants are insect pollinated and must be able to attract pollinators without trapping them. All of the plant species go through a dormant period as seasonal temperatures get cooler. Traps die back and are regrown when warmer weather returns. In several species, flowers bloom and attract pollinators with nectar, completing fertilization before traps develop. Other plants separate the flowers and traps by a physical distance. Traps usually lie close to ground level to attract crawling insects, and flowers are grown on top of tall stalks to attract flying insects. A third method is to make the flowers less attractive to potential prey, and make the traps less attractive to potential pollinators. This is achieved by using different colors, patterns, and scents on flowers and traps.

^{Metallic green sweat bee, Agapostemon sericeus by Dann Thombs, Aug 2008}

^{Cobra lily, Darlingtonia californica by Charles Peterson, Mar 2018}

Whether you are growing these unique plants at home or viewing them in a botanical garden or out in the wild, some of the plants and their pollinators to watch for include the white-topped pitcher plant, Sarracenia leucophylla and the two-spotted bumblebee, Bombus bimaculatus; the cobra lily, Darlingtonia californica and the mining bee, Andrena nigrihirta, Tracy’s sundew, Drosera tracyi and the metallic green sweat bee, Agapostemon sericeus, and the Venus flytrap, Dionaea muscipula and any of the hoverfly species, Toxomerus sp.

^{Bog landscape by Chris Moody, Jun 2009}

Buttonbush

Over the past several days, there has been a lot of activity in our backyard pollinator garden in the area surrounding the buttonbush, Cephalanthus occidentalis. This native shrub is a multi-stemmed flowering species that can grow from 3′ to more than 12′ tall. It needs lots of sunshine and prefers moist soils. Found in many habitats including sub-tropical swamps, shrub swamps in the northeast and upper Midwest, and southern and northern floodplain forests east of the Mississippi, this species prefers swampy backwater areas, marshes, wet meadow and bogs.

^{Buttonbush, Cephalanthus occidentalis, whorled leaves by loonyhiker, Oct 2010}

Newer stems are green, but quickly turn dark brown to almost black, becoming scaly with age. Leaves are opposite or whorled around the stem, each one protruding at a slightly different angle than the one above. It is thought that this arrangement provides maximum exposure of the plant’s total leaf surface to the sun.

^{Buttonbush flowers by DonArnold, Jul 2023}

^{Bumblebee on buttonbush by DonArnold, Jul 2023}

The flower clusters appear as small balls between 1/2″ and 1″ in diameter, with over 200 spikes poking outward covering their entire surface. Each spike is actually an individual flower. Flowers are closely grouped together and exude an intense, sweet fragrance. The plant reproduces through a two-stage cycle where pollen is produced and falls onto the immature pistil. As visiting insects brush through the closely grouped flowers, pollen rubs off onto their bodies. Once the pollen is gone, the pistil matures and becomes sticky at the end. As other insects arrive, pollen from other plants is picked up by the sticky end to pollinate the plant.

After pollination is complete, and the flowers drop off the plant, the ball-shaped seedhead turns completely brown. Unless it is brushed off by a passing animal or it is eaten, the seedhead may remain with the plant through the entire winter season, dropping off in spring. Seeds will often disperse into wetland areas, floating to shore. Each seed ball contains two nutlets.

^{Red Admiral butterfly on buttonbush by DonArnold, Jul 2023; Honney bee on buttonbush by DonArnold, Jul 2023; Long-tongued tiger swallowtail on buttonbush by Owen Sholes, Getty Images}

Pollinators include many long-tongued insect species especially bumblebees, honey bees, tiger swallowtail butterflies and black swallowtail butterflies. In addition, over two dozen bird species utilize the shrub for food, shelter, and nest building material – most notably are wood ducks that use the plant’s structure to shelter their young. Amphibians and reptiles hide among clusters of buttonbush in wetland areas for protection during the breeding season. Several honey-producing bee species are attracted to its pollen and nectar.

^{Buttonbush, Cephalanthus occidentalis, by NC Wetlands, Aug 2018}

With more than a dozen buttonbush species worldwide, it is an easy plant find and get close to for observing its flowers and fruits, as well as the behaviors of the many animal species that frequent this shrub.

Bee An Early Pollinator

There are over 20,000 species of bees world-wide, and more species are found every year. Bees are important pollinators, especially in early springtime. Other pollinator species abound, and all are important to the life-cycle of flowers, but bees are thought to increase seed production by about 70%.

^{Dandelions on day 100 by Mike Deal, Apr 2010}

The bees we see in our gardens are all adults, emerging from their nests between early spring and late summer. The first to emerge are the bumblebees. They have wingbeats of about 200 strokes per minute and a metabolic rate that is double that of a hummingbird, allowing them to generate plenty of body heat to stay warm during cool spring weather. Orchard bees are the next out as soon as daily temperatures stay in the mid-50s. Native honeybees may also come out at about this time, but imported bees cannot fly in temperatures less than 60˚F. Early blooming flowers including dandelion, jewelweed, aster, goldenrod, and clover, are important sources for pollen and nectar in spring.

^{Honeybee covered in zucchini pollen by John Kimbler, Getty Images}

As crop plants start to flower, including fruit trees and vegetables, a large pollinator workforce is needed. Almost one-third of the food consumed by humans comes from plants requiring pollination. As pollen is collected by bees, the grains are spread over the bee’s body, allowing some of those grains to rub off and pollinate subsequent plants as the bee follows a route visiting various flowers. Adult bees feed mostly on nectar, eating very little of the pollen they collect. Pollen is brought to the nest to feed their young.

^{Bumblebee in flight with loaded corbicula by mirceax, Getty Images}

Honeybees and bumblebees have a bare spot on their back leg called a corbicula, surrounded by inward curving hairs. As pollen is collected from each flower, it is scraped into this holding area, which may amount to 20% of their body weight while in flight. After landing, a bee grips a flower tightly with its jaws and legs. Snuggling close to the anthers, the bee vibrates and dances to disrupt the pollen inside and let it fall onto their bodies. They proceed to groom all the pollen grains into the corbicula before moving onto the next blossom. When the corbicula full, the bee will fly straight to the nest, unload all of the pollen, and return immediately to where they left off to collect more.

^{Honeybee collecting pollen into scopa by baianliang, Getty Images Signature}

Other bees store pollen in scopa, tufts of hair on their legs and abdomens. As pollen covers the bee during its flower visits, the four front legs are used to scrape the pollen down past their abdomen where the two back legs pack it into the scopa. Some bees may carry the pollen dry, and others may mix in a little nectar to form a dough-like substance that easily sticks to their body hair.

Brown honeybee heading into narrow opening by Gregory Johnston

Buzz pollination video @ This Vibrating Bumblebee Unlocks a Flower’s Hidden Treasure | Deep Look

Pollen collection has resulted in the development of several adaptations found among many bee species. Electrostatically charged body hair attracts pollen. The charge is a result of air moving across the body while the bee is in flight. When plants are small enough that only the bee’s head fits inside, hooked hairs on faces and under chins allow easy pollen collection. Some plants keep pollen in anthers, long tubes that must be turned upside down and shaken to release the pollen. Many bee species use buzz pollination, hanging onto the anthers to tip them, then vibrating their wing muscles to loosen the pollen, allowing it to fall on themselves.

^{Red head bee, Pachyprosopis eucyrta, licking up nectar by Jean&Fred Hort, Mar 2014}

Nectar provides carbohydrates in the form of sugars and amino acids. Bees use their tongues to lick it or suck it up. Several species have longer tongues for use on deep-necked flowers. Honeybees collect nectar and bring it back to their hives to store it. Over time, some of the water content evaporates, forming honey. This is used as food over winter or at times when other food is scarce. Some bumblebees have been shown to also collect and return nectar to the hive, but don’t create true honey. This nectar is used as nourishment for the hive-bound queen only, not as a food source for the entire colony.

As we begin to see the many blossoms of spring and summer, remember that adult bees are only out in our gardens for a short period of their lives. We can assist their work as pollinators by allowing early spring flowers to finish their blooms before cutting them down.