Common Milkweed Pollination
The structure of the Common Milkweed (Asclepias syriaca ) flower is such that its pollen, produced in two saddlebag-like sacs with a black appendage joining them, snaps onto an insect’s leg when the two come in contact with each other. To assure that the chances of this are high, the pollen sacs (pollinia) hang inside a slit that is located between each of the five cups, or hoods, that contain nectar. An insect lands on the slippery flower, attracted by both the scent and availability of nectar, and inadvertently one or more of its six legs slips down between the hoods into a slit, where the pollinia automatically attach to the leg. The insect withdraws the leg upon leaving to find more milkweed nectar, and the attached pollinia eventually falls off onto another milkweed flower, pollinating it. Unfortunately, about 5% of milkweed flowers visited trap insects because they cannot extract their legs from the slit. It is not uncommon to see an insect dangling from a Common Milkweed flower – during a 30 minute visit to a milkweed patch recently I released 2 flies, 3 skippers (butterflies) and one honeybee that were caught, but hadn’t yet perished.Hummingbird Clearwing Moth
Of all the insects I’ve found in milkweed patches over the years, the Hummingbird Clearwing is one of my favorites. It is a species of sphinx moth, named for its habit of hovering at flowers while it gathers nectar with its proboscis in a manner similar to that of hummingbirds. In fact, they are often mistaken for hummingbirds. The transparent wings, light brown thorax and dark chestnut abdomen are the field marks to look for. A diurnal moth, the Hummingbird Clearwing can often be found during the day in milkweed patches.
Milkweed Visitors
Milkweed is in full bloom right now, presenting the perfect opportunity for young and old alike to discover the multitude of butterflies, beetles, bees and other insects that are attracted to these magnificent flowers. If you visit a milkweed patch, don’t leave before getting a good whiff of the flowers’ scent – one of the sweetest on earth. How many of the insects you find are carrying milkweed’s yellow pollen “saddlebags” on their feet? You might want to check out my children’s book, MILKWEED VISITORS, which I wrote after spending the better part of one summer photographing the various insects I found visiting a milkweed patch. ( http://basrelief.org/Pages/MV.html )
Blue-eyed Grass
It’s easy to miss Blue-eyed Grass (Sisyrinchium angustifolium), as its flower is only about ½” in diameter and the plant only reaches a height of six to twelve inches. Blue-eyed Grass is a member of the Iris family, not, as its name implies, a member of the Grass family, although it does have stiff, grass-like leaves. Dark lines on its petals and sepals may well serve as nectar guides, leading pollinators to the yellow center. Each blossom is open for only a day at most. Typically you find Blue-eyed grass growing in sunny, wet fields, often on elevated soil — Thoreau noted that if you followed Blue-eyed Grass through a wet meadow, you could keep your feet dry.
Pitcher Plant Flowers
The Pitcher Plant (Sarracenia purpurea) is a well-known carnivorous plant of bogs. It gets some of its nutrients by trapping and drowning prey in rain water that is caught inside a modified leaf that forms a cup. While most people are familiar with the leaves of Pitcher Plants, unless you visit a bog in June, you’re not likely to see their unique flower. It is curved over when it’s mature and its sepals (modified leaves that protect the bud and are located above the petals in these photographs) are red-purple and pointed; the petals are red and rounded. An approaching insect would be guided into the flower between two of the sepals–it would land on a petal and climb into the flower onto the umbrella-shaped stigma (the sticky top of the female pistil) which I inverted in one photograph in order to show the male pollen-producing stamens. An insect entering the flower would brush against the stamens, collecting pollen on its back while pollen from a previously-visited Pitcher Plant would fall off the insect onto the sticky stigma on which it was standing, pollinating the flower.Fringed Polygala
Fringed Polygala (Polygala paucifolia) looks a bit like a miniature orchid, but it is not — it is in the Milkwort family. The structure of its ¾-inch bright magenta-pink blossoms is well-suited for its bumblebee pollinators. The bee lands on the pink fringe at the front of the flower and its weight triggers the white “keel” to drop down. A slit at the keel’s top opens, exposing the reproductive parts of the flower. Pollen from the stamens is rubbed onto the bee’s hairs while it probes deeply into the base of the flower for nectar, while pollen from a previously visited Fringed Polygala is scraped off onto the stigma, where it needs to be in order for fertilization to take place.
Red-necked False Blister Beetle
If you find a blossoming Trout Lily in the woods it is quite likely that you will also find one of its most common pollinators, the Red-necked False Blister Beetle (Asclera ruficollis), on it. Ardent pollen eaters, this group of beetles obtain their common name because many species cause blisters when pinched or squashed against skin. Adults mate on flower heads during pollen feeding. Both sexes feed on pollen, which acts as an attractant, but the female will not accept the male until her gut is packed full of pollen. She stores the pollen in a special intestinal sack in which an enzyme causes the pollen to partially germinate — this causes the indigestible covering of the pollen grain to rupture. She then digests the contents of the pollen grain, which she uses to manufacture eggs.
Spring Beauty Pollinators
Spring Beauty (Claytonia virginica) is one of our earliest woodland wildflowers to blossom, and thus an important source of nectar and pollen for the earliest foraging insects. Pink lines (“bee guides”) on each of its five petals lead pollinators to the center of the flower, where the nectar is located. The pollinator in this image, Andrena erigeniae, is one of the more common species of bees that visits Spring Beauty in the early spring. Notice the slightly pink pollen she has gathered into the pollen basket on her hind leg. If you’re interested in spending time observing the series of different insect pollinators that visit Spring Beauty as the season progresses, there’s a golden opportunity for you. If you go to http://springbeauties.wordpress.com/ you can participate as a citizen scientist volunteer and participate in their survey.
Sulphur Butterflies
It’s hard to believe, but even after Irene, several inches of snow and an occasional night that’s below freezing, there are still butterflies and moths to be seen. Yesterday this sulphur butterfly (probably clouded, Colias philodice) was flying from dandelion to dandelion, sucking up nectar with its long, black proboscis. Clouded sulphur and orange sulphur butterflies, two different species, are similar looking, and on top of that, they even hybridize, so distinguishing between the two is often difficult, at best. Both species have several broods in a summer; you can see them flying in fields and along roadsides from spring to fall.
Bottle Gentian
One of our latest flowering plants is the brilliant blue bottle, or closed, gentian (Gentiana andrewsii ). It is so-called because the tips of its petals come together like the neck of a bottle, protecting the nectar from rain. The lure of bottle gentian for insects is both the abundance of nectar, as well as its high (40%) sugar content . Only the strongest of insects, however, are able to struggle their way down into the flower in order to reach the nectaries. Because of their strength and perseverance, bumblebees are the primary pollinator of bottle gentian. Once a flower has been visited and its nectar collected, the tips of its petals turn white, signaling other bees that it would be a waste of time and energy to fight their way into the flower. (Yellow lumps are pollen in the bee’s pollen baskets, specialized hairs on the bee’s hind legs.)
Nodding Ladies’ Tresses
The downward “nodding” curve of its tubular flowers gives Nodding Ladies’ Tresses (Spiranthes cernua) part of its common name. ( I’m not sure where the reference to tresses, or a woman’s long locks or braid of hair, comes from.) The bright white flower spike of this relatively common member of the Orchid family stands out in moist meadows of green grasses. A perennial, Nodding Ladies’ Tresses grows between 4 and 12 inches tall, and is pollinated by both long and short-tongued nectar-seeking bees.
Goldenrod Visitors
If you want to get an idea of the number and variety of wasps, bees, beetles and bugs that reside in your area, go to the nearest goldenrod patch sit for a spell – this member of the Aster family is a magnet for insects. You’ll find many foliage- eating bugs and beetles, leaf-mining larvae, nectar and pollen feeders, and flower and seed-eaters. In addition, many predatory spiders (jumping and crab, especially) and insects (ambush bugs, ladybug beetles, flower bugs etc.) have discovered that goldenrod is a goldmine for them, as well. Researchers have found nearly 250 species of insects feeding on one species of goldenrod (Solidago canadensis). Pictured from left to right are a long-horned beetle (locust borer, Megacyllene robiniae – pollen eater), a fly (nectar feeder) and bee (nectar and pollen feeder).
Ruby-throated Hummingbird
Ruby-throated Hummingbirds, New England’s only species of hummingbird, are a major pollinator of flowers. As they hover at flowers, often red like the pictured bee-balm, hummingbirds probe their bill down into the flower’s nectaries in order to reach the nectar. As they do so, the anthers of the flower brush against the hummingbird, often on top of its head or on its face, depositing pollen. Some of this pollen is likely to fall off on the strategically placed stigma of the next flower it visits (often the same species). Research in Illinois and Missouri confirms that ruby-throated hummingbirds deposit ten times as much pollen (per stigma per visit) as do bumble bees and honey bees! The diet of hummingbirds is not limited to nectar, however. Insects, including caterpillars, mosquitoes, spiders, gnats, fruit flies and small bees, are gleaned from leaves and bark, as well as captured in air. The sap holes drilled in trees by yellow-bellied sapsuckers attract insects which hummingbirds consume along with the sap.
Naturally Curious with Mary Holland 
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