After a quick glance at graphics on this page, it might appear we went a little heavy on yellow. Indeed, all but the bottom four photos depict an insect perched on Goldenrod flower heads at Hilton Pond Center, so you might conclude that this week's installment is about Solidago--the numerous species of brilliant yellow native Goldenrods that brighten autumn days. Actually, however, our current photo essay is about the insects themselves--and about other organisms that play critical roles as pollinators of flowering plants. Even though we'd all be in a heap of trouble without pollinators, most humans ignore their value and at worst eradicate them with indiscriminate pesticide application, habitat destruction, and other endeavors. Pollinators are worth protecting for their own sakes, but we would do well to remember that these creatures facilitate reproduction in 90% of the world's flowering plants, and that--on average--one in every three bites of food we humans take comes courtesy of an animal pollinator.

All text & photos © Hilton Pond Center

We've been thinking a lot about pollination, in part because this week we were in College Park, Maryland taking part in a major meeting of the North American Pollinator Protection Campaign (NAPPC). The mission of this group--made up of researchers, educators, government officials, conservationists, and industry representatives from the U.S, Mexico, and Canada--is "to encourage the health of resident and migratory pollinating animals in North America," and there are a lot more of these animals than one might realize. Their diversity is illustrated by the photos herein--all but three of which were taken in a brief one-hour span this week in a Goldenrod patch at Hilton Pond Center.

When one hears the word "pollinator," one typically thinks of Honey Bees, whose value and industrious visits to flowers are known even to a casual nature observer. Indeed, European Honey Bees, Apis mellifera, are significant pollinators of many agricultural crops and native plants; the massive orange pollen sac on the hind leg of a worker Honey Bee (above left) is evidence of her pollen-transferring activities. Honeybees, however, are non-native; they were brought from Europe by early settlers who wanted honey on their breakfast biscuits, so these imported insects very likely displaced many native pollinators already hard at work across North America. The big question is: "Who was doing the pollinating before the arrival of Honey Bees?" And the bigger answer is: "A hugely diverse assortment of insects--and even a few vertebrates!"

Among the most common native pollinators are "solitary bees," so-called because they don't assemble in hives or colonies like social Honey Bees. Solitary bees--some less than an eighth of an inch long--are at least as busy as Honeybees but are often overlooked even though they pollinate valuable commercial crops such as strawberries. Perhaps the most visible native solitary bee is the roly-poly inch-long Carpenter Bee, Xylocopa virginica (female above right), which resembles social Bumble Bees. All these big pollinator bees have fuzzy thoraxes--the yellow body segment behind the head--but can be differentiated because the top of the Bumble Bee's abdomen is fuzzy while that of the Carpenter Bee is smooth and shiny.

As small as the smaller solitary bees are some flies that also pollinate, including the quarter-inch-long unidentified species (Eristalis, perhaps?) in the photo below left. Some flies superficially resemble bees since both have wings that are transparent and membranous, but flies bear only two wings while bees have four. Most folks are already aware that flies are attracted to sugar--spill a soft drink on the ground and a swarm of them likely will arrive in short order--so it's not surprising that flies visit flowers in search of sweet nectar. While lapping up this carbohydrate-laden treat with their long, extensible mouth parts (see photo), flies also pick up a little pollen and transfer it to the next flower they visit. Flies and solitary bees don't have pollen baskets (corbiculae) like Honey Bees and Bumble Bees, but female solitary bees do have modified structures such as hairs on their legs or abdomens that help facilitate pollen collection.

Another pollinating group that is often forgotten is the wasps, which--like their bee relatives--have four wings. One wasp we spotted this week in the Hilton Pond Goldenrod patch was obviously in pursuit of spiders to take back to imprison in her nest; when the wasp's eggs eventually hatch, her larvae will dine from their eight-legged larder. Most of the wasps, however, were placidly crawling around on flower heads, consuming nectar and not nearly as aggressive as they would be under other conditions. We detected at least two species of large wasps (Polistes sp. at upper right), but some pollinating wasps are as small as some of the miniature flies and solitary bees that visit flowers.

And then we have the beetles. There are more beetles in the world than any other insect group--750,000 species and counting--so it stands to reason some of them would be involved in the business of pollinating. Again, there are big beetles that visit flowers, including the nearly inch-long Black Blister Beetles, Epicauta pennsylvanica, that were all over our Hilton Pond Goldenrods (top photo), but many pollinating beetles are quite small; without a hand lens they look like mere black specks on flowers. Beetles stumble about in the blossoms, bumping up against stamens that deposit their sticky pollen on various beetle parts--a "roil and soil" process facilitated in some beetle species by a fine layer of fuzz.

Many adult butterflies are also nectar eaters and important pollinators--which shouldn't be a surprise when we consider how many millions of exotic Butterfly Bushes, Buddleja davidii, have been planted in recent years by homeowners trying to attract these colorful insects. While we were taking photos this week, a somewhat raggedy Viceroy butterfly, Limenitis archippus, fluttered in and stopped for a while on the Goldenrods (above left). This Monarch-mimic flitted from flower to flower for tasty sugar snacks, eventually moving up to the treetops and out of our field of view.

As the Viceroy departed, our attention was attracted to an unusual day-active moth that pollinates flowers. It was an inch-long Yellow-collared Scape Moth, Cisseps fulvicollis, whose uncoiled red proboscis can be seen probing a Goldenrod inflorescence in the photo above right. The vast majority of moths are nocturnal, of course, and some are very important pollinators of night-blooming flowers, especially in desert regions of the southwestern U.S. and Mexico. For example, the female Yucca Moth, Tegeticula maculata , has mouth parts that allow her to gather a ball of pollen under which she lays her eggs in the stigma of a yucca flower--which also insures that yucca cross-pollination occurs.

It's a little-known fact that some plants with nocturnal blossoms-- particularly in the tropics--are pollinated not by moths, but by bats. These flying mammals that strike fear in humans who have seen too many vampire movies include species with tongues adapted for lapping up nectar. The elongated snout of Musonycteris harrisonii (left) is perfect for probing flowers of a tropical tree that has significant importance to most North Americans--hence its common name of "Banana Bat." Just imagine breakfast or peanut better sandwiches if it weren't for the pollinating behavior of this long-nosed tropical bat!

In the eastern U.S. and Canada flying animals other than bats are also important pollinators, but these have feathery wings and happen to be very dear to our hearts here at Hilton Pond Center. We refer to Ruby-throated Hummingbirds, Archilochus colubris, which visit all sorts of native and imported flowers in search of nectar, from Red Columbines in spring to the Cardinal Flowers of autumn. For anyone who has noticed a hummer with a smear of white or yellow powder on its forehead or bill (below), there can be little doubt that hummingbirds play a role in pollinating. The hummer's long thin bill is perfectly adapted to the deep tubular flower of plants like Trumpet Creeper, Campsis radicans--perhaps the single most important native hummingbird plant in eastern North America (bottom photo).

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Birds, beetles, bats, bees, butterflies--even wasps and flies. We've touched upon all these pollinators but barely scratched the surface in describing their diversity and how important they are, both environmentally and economically. In short, without pollinators the world of nature AND humans goes hungry, so animals that carry out this business of flower fertilization need understanding and protection--not just at Hilton Pond but everywhere they occur. Next time you're ready to grab a spray can of insecticide or are tempted to use the mower on a patch of "weedy" Goldenrods in the backyard, remember your actions may wipe out an entire assemblage of important local pollinators. That literally could upset the old apple cart--a cart that otherwise would be filled by fruits cross-pollinated by wasps or beetles in the orchard down the lane.

SPECIES BANDED THIS WEEK:
Eastern Phoebe--2 *
Magnolia Warbler--6
Black-throated Blue Warbler--2
Cape May Warbler--2
Yellow-rumped Warbler--2
Northern Cardinal--5
Gray-cheeked Thrush--2
Swainson's Thrush--1
Red-bellied Woodpecker--1*
Mourning Dove--1

* = New species for 2003

Yellow-rumped (Myrtle) Warbler
Note the partial eye ring

OTHER SIGHTINGS OF INTEREST
--We were heartened by the arrival of two Yellow-rumped Warblers this week (photo above). This species--still the fifth most commonly captured in our nets with 1,851 birds since 1982--has declined greatly around Hilton Pond. We banded 425 in 1991 and 248 in 1994, but have averaged only 31 "butter-butts" per year over the past seven years.

--Nearly all the warblers and thrushes banded this week at Hilton Pond Center were laden with yellow fat. These energy-rich deposits are laid down primarily in the furcula, the wishbone area below the throat. It's curious that so much fat is put on well before these migrants get to a coastal "jumping off" point as they make their way to Central or South America.

--Since no Ruby-throated Hummingbirds were banded this week at the Center, we suspect our "summer hummer" activity is over for the year. Bring on the winter vagrants!

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