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.