Perfume and Pollination 1 - The Privet

 

Border Privet, Ligustrum obtusifolium

During the month of June privet shrubs come into flower at Halibut Point. You're likely to notice their fragrance before you even see the little ivory blossoms. Strong fragrance and white petals is a combination often employed by plants that attract night-flying pollinators such as moths, which are reputed to visit privets in the dark. That attribute I have not personally verified by camera in the nocturnal forests of our State Park. As in so many other dimensions I borrow freely from the science of naturalists to deepen the pleasure of what I can see before my eyes.

Halictid bee on privet blossom

Privet shrubs sponsor a champion pollination program, which produces such masses of berries that privet progeny rival bittersweet at the top of the regional invasive plant list. I have gazed (during daylight)  at thousands of privet shrubs blooming this month in the Park. Oddly, only bees have responded to their nectar-for-pollination invitation. It's as though the invitation is scented "Only bees need apply." Myriad other insect types fly, hop, or crawl right on by without stopping.

Leafcutter bee

What leads to such a narrowed clientele? I wondered if it had something to do with the tubular shape of the flowers that puts the reward deep within, where only long-tongued partners could reach it as they covered themselves with pollen during the forage. But the bees observably concentrate their attention at the entrance rather than the recesses of the blossom.

Bicolored striped-sweat bee

It seems more likely that the selective message lies within the realm of smell, where privets are not at all shy. They saturate the air with a tropical muskiness that to my nose suggests honey and vanilla. One blogging commentator opines that "there is a class of fragrance that lies somewhere between perfume and scent" and that privet's "sweet, pungent scent has been likened to the scent of an animal." Human reaction to privet fragrance is quite partisan, perhaps parallel to responses in the insect world.

Bumblebee approaching privet flowers

When Hampton Sun, a producer of luxury cosmetic products, launched its Privet Bloom brand in 2007 a reviewer ranted that it "really should be advertised as a home fragrance rather than a personal one....it smells most like a big duffel bag used as a beach bag [that] was left by a blooming privet hedge, next to a bag of ripe plums. It is choke full of toiletries and makeup and the scents of powders and lipsticks are raging inside the bag under the sun."

Honeybee

Bee that as it may, privet flowers are highly popular with industrious apiary workers intent on bringing rich nourishment back to the hive.

Eastern Tiger Swallowtail on privet in bloom

Their allure to a Swallowtail butterfly in a past season provided my only recorded sighting of a non-apiary visitor to privet flowers. This souvenir image fully completes the richness if not the rarity of that moment. 

Seductive Sumac

 

Staghorn Sumac in flower

Staghorn Sumac is well known on the Halibut Point landscape for its brilliant fall foliage and its clusters of reddish berries that support winter wildlife. Its panicles of tiny greenish-white-to-yellow flowers that are blooming now draw less notice from human eyes but are very popular with insects, especially bees. Their attraction to pollinators must be partly by a fragrance that escapes our senses but compels visits by flying creatures.

Western Honeybee, Apis mellifera

Honey, bumble, and other bees within the family Apidae are equipped with pollen baskets called corbiculae to bring their harvests back to the hive. 

Taxonomic note: in the scientific system of providing unique names for flora and fauna as adapted here, Apidae is one of several different families of bees each consisting of multiple closely related forms (genera, the plural of genus); Apis is the genus; and mellifera, the species name designating a unique form within Apis.

Yellow-banded Bumble Bee, Bombus terricola

Although they superficially look different, Common Bumblebees and other members of the Bombus genus such as this Yellow-banded Bumblebee are assigned by taxonomists to Apidae along with honeybees because of similar anatomic details, e.g. pollen baskets. Both are organized in social colonies, although bumblebees usually nest underground. 

Syrphid fly, Eristalis transversa

Some foragers to the sumac come in bee disguise as a protective evolutionary adaptation in appearance rather than anatomy. Many species of syrphid flies (flies comprise the taxonomic order Diptera, meaning 'two-winged') superficially resemble bees (of the taxonomic order Hymenoptera, meaning 'membrane-winged'). All bees have four wings.

Bicolored Striped-Sweat bee, Agapostemon virescens, family Halictidae

Bees of the family Halictidae are solitary ground nesters often showing metallic coloration. Their hind legs are flattened and covered with hairs to carry pollen.

Leafcutter and Resin Bees, family Megachilidae

Leafcutter bees, in another variation, carry pollen on the undersides of their abdomens to solitary nests in natural cavities they find in wood or in the ground, that they line with pieces of leaves.

Spotted Nomad, Nomada maculata

Spotted Nomad bees derive some protection from their resemblance to more aggressive wasps. They are nearly hairless, as they don't have to carry pollen back to a brood. Their method of laying eggs in other species' nests, where their larvae eat the host egg and pollen supply, earns them the name Cuckoo Bees after the parasitic birds that lay their eggs in other species' nests.

Thread-waisted Wasp, Ammophila nigricans

Some true wasps are also attracted to feed on sumac flowers in exchange for pollination.

A Parasitic Fly of the family Tachinidae

Insect visits to sumac trees pick up as the day goes on, in a complex cycle of attraction to the male and female flowers that grow on different plants. Most honeybee activity is concentrated on male inflorescences in the late morning and on female ones during the afternoon, according to the plants' secretion pattern of pollen and nectar.

Window-winged Moth, Pseudothyris sepulchralis

In the case of sumacs, by far the greatest numbers of pollinators are bees. A few lepidoptera (moths and butterflies) benefit from the sumac's particular flower structure, nourishment, scent and appearance.

American Lady butterfly, Vanessa virginiensis

As with most relationships in the living world interdependent existences promote mutual survival.

Sources

Tom Murray, Insects of New England & New York, 2012. 

Carlos F. Greco, Dean Holland, and Peter G. Kevan, "Foraging Behaviour of Honey Bees on Staghorn Sumac," The Canadian Entomologist vol. 128, May/June 1996.

The One that Got Away

This has been dragonfly week at Halibut Point, a welcome replacement in the Department of Aerial Dazzle since the spring bird migrants have either moved on or disappeared within the leaf canopy. It's time to dust off the laminated Guide edited by local naturalist  Chris Leahy during his tenure at Mass Audubon. Off we go to look for old acquaintances darting over fields and ponds, with the hope of a new discovery or two.

The overlording creature on the Guide cover earned his prominence not only from brash coloration and a chesty profile but from his masterly patrols over wetlands.

Common Green Darner

And sure enough, recently the Green Darners have resumed their station at the pond by the old quarry power plant.

An unexpected rival appears

Suddenly a robust  presence I didn't recognize entered the Darner's presumptive realm.

Black Saddlebags dragonfly

Its broad wings, chunky fuselage, and dark cloak all projected dominance. Chris identified it from the photograph. The Black Saddlebags dragonfly isn't portrayed in the pocket guide because it's generally a migrant species through this area, which is probably a good thing for Darners.

Eastern Forktail

On a more delicate scale it was nice to be able to compose this portrait of an Eastern Forktail damselfly.

Violet Dancer and Eastern Forktail

I appreciated its array of colors beside a Violet Dancer.

Ebony Jewelwing, central on the Guide cover

For the briefest moment a butterfly-like Ebony Jewelwing fluttered by. It posed on a twig in a shaft of sunlight and disappeared while I fumbled with my camera. Normally it lives along flowing streams and I may never see one again on Halibut Point. But ah, the glimpse is indelible.

Lancet Clubtail dragonfly

As partial compensation this Lancet Clubtail appeared, a novelty for me on the Halibut Point rambles.

Warbler Gallery

The migrating warblers have continued on to northerly regions that suit their breeding needs. Briefly they created an enchanted woodland at Halibut Point. Bird watchers flocked to the sport and spectacle of identifying exotic species.  Photographers sought souvenirs of treasured encounters. Here are some portraits not featured in earlier postings.

Wilson's Warbler

Nashville Warbler

Pine Warbler

Common Yellowthroat

Tennessee Warbler

Ovenbird

Magnolia Warbler

Chestnut-sided Warbler