New England Aster (Symphyotricum novae-angliae). A multitude of open, closed, fertilized and unfertilized blossoms. Photo by Donna L. Long.
From my nature journal – October 14, 2015
The New England Asters in my garden have finished blooming. The deep pink flowers began opening in late September and had a crowd of bees, flies, and beetles around the blossoms until last week.
New England Asters (Symphyotrichum novae-angliae) are native from Massachusetts and Vermont to North Dakota and Wyoming, south to New Mexico and Virginia at higher elevations. These lovely colorful late autumn flowers have spread themselves far and wide across the continent. They are one of my favorite autumn flowers.
Prune the Asters in June
The asters in my garden are a pinky-purple color. They can grow to 2-3 feet tall or even 6 feet, but I prune the stems back by half in June and again in early July to keep the plant at a manageable height.
New England Asters are often struck by leaf blights that can turn the leaves an annoying powdery-gray color, which I ignore. Of course if you have the room you can plant this flower behind a lower growing plant which will hide its dusty legs.
The Ray Flowers of the Asters
The pinky-purple petals are really sterile ray flowers. The centers are a collection of many small fertile flowers, filled with nectar and pollen. The golden centers is where all the insect action happens. The golden centers are filled with 45-100 ray flowers, which is 45-100 sources of nectar and pollen on one flower.
This explains why these plants are so popular with insects. While perched on one flower head an insect can collect nectar from 45 to 100 flowers instead of one blossom.
New England Aster as a Host plant
New England Aster is a larval host plant for several Crescent butterflies (Pearl, Tawny, and Field) The Canadian Soma Moth, and the Mining Bee. All this makes the plant fascinating to observe.
The Nectar of the New England Aster
I have watched a variety of bees, flies and beetles foraging among the many ray flowers. They collect nectar and pollen to feed themselves and any eggs or larva they have back in their nests.
Nectar is a sweet liquid produced by plants and consists primarily of water and varying concentrations of sugars including fructose, glucose, and sucrose. Nectar is a major energy source in animals diets. Nectar is produced in structures called nectaries located at the bottom of petals or other places on a plant.
The Pollen of the New England Aster
Pollen, the other substance insects clamor for, is an important source of protein along with fats, starches, vitamins and minerals. Pollen is between 2.5 and 61 percent protein.
Nectar and pollen are important food sources for both adult insects and their larva. Nectar and pollen are main ingredients in bee bread. Female bees make bee bread and place it in nest cell and lay eggs on top of it. The egg hatches and the emerged larva feeds on the bee bread.
New England Asters, Beetles, and Bees
The New England Aster flowers in my garden are visited by a variety of insects. Who visits what flowers are because of the color, shape, scent, and when the flower is open and other factors.
I saw Spotted Cucumber Beetles (Diabrotica undecumpunctata), Arciegera Flower Moth (Schinina arcigera) and larva, an unidentified wasp and tiny flies I could barely see.
The bee visitors included several Large Carpenter Bees, a Bumble Bee (Bombus spp.) and a Honey Bee (Apis mollifiera). I didn’t recognize the Honey Bee as a Honey Bee because I wasn’t expecting to see it.
With honey bee colonies collapsing I hadn’t seen one in a while. But, there are beekeepers in Philadelphia and my section of the city. Perhaps. the honey bee was from one to the beekeeping colonies or a free and uncultivated hive.
The Arciegera Flower Moth and the Asters
The Arciegera Flower Moth was a surprise. I had seen this small brown moth fly around my garden but didn’t know what they were. These moths range from Eastern North America from Manitoba east to Nova Scotia and South to Florida and Texas. They are active from summer to late fall.
The moth was sipping nectar like so many of the other insects on the asters. These moths mate in the fall, and lay eggs. A found a tiny Arciegara Flower Moth in the blossoms of an aster.
The tiny larva feed on the flowers, fruit and seeds of the aster, their host plants. (link to why native plants) The larva will change or pupate in late fall and overwinter in the ground as a pupae and emerge next summer as an adult moth.
Large Carpenter and the Asters
Large Carpenter Bee (Xylcopa spp.) with new blossoms, fertilized and blossoms going to seed of a New England Aster (Symphyotricum novae-angliae) in my garden.
I am fascinated by the huge size of the Large Carpenter Bees (Xylocopa spp.). I think this bee is female as she has a dark face. Male Carpenter Bees have pale faces. This female bee is large, strong, and hard-working. She reminds me of the woman in the “Rosie the Riveter” World War II poster.
I watch this Large Carpenter Bee as she goes about the collection of pollen and nectar in the bright pink blossoms. I stand quite close and she ignores my presence. I see her poke her long tongue into the golden center of the asters. It reminds me of a needle moving up and down on a sewing machine.
Her pollen sacks on her leg are empty. She must be back from emptying her sacks back at her nest perhaps in the ground nearby.
The Large Carpenter bees have bright yellow fuzzy jackets (thoraxes) and shiny black abdomens. Large Carpenter bees are solitary bees. The female builds the nest and stores food on her own without help from others. The nests are typically hollow stems or holes in wood.
I noticed two sizes of Large Carpenter Bees Since these bees aren’t social bees with queens and hives, the large bee can’t be a large queen and the smaller bee isn’t a smaller worker.
In some species of hive bees some female bees are fed more food so they will grow larger, over winter and go off on their own the following spring emerge as queen bees of their own hives. I guess they are just two different sizes. Or the smaller bee might be a male or they might be two different species of Carpenter Bee.
How Bees Collect Pollen
Bees collect pollen in two ways, in pollen baskets on their legs, or in a crop in their abdomen (a pouch enlargement of the esophagus) where it stores the collected pollen and nectar until it returns to its nest.
The Large Carpenter Bees on the New England Asters rake the pollen from the anthers with their mouthparts with comb-like structures on their legs.
The large Rosie the Riveter bee I watched, would have combed pollen from her head, throat, and abdomen and deposited it into the pollen sacks on her legs. She would have used the pollen and nectar to make bee bread to feed her offspring when they hatched next spring and she isn’t around having died this fall.
The New England Asters in my garden are finished blooming. The flower heads are shriveled and brown. The flowers are making seeds now. Many of the seeds will feed the birds that visit my garden throughout the winter.
For more information native plants and pollination:
Pollinators of Native Plants: Attract, Observe and Identify Pollinators and Beneficial Insects with Native Plants by Heather Holm – This book has on the hows and whys of pollination and how pollinators and native plants interact.
Attracting Native Pollinators: Protecting North America’s Bees and Butterflies by the Xerxes Society