Flowering plants are living beings that need to reproduce, but they’re immobile. So, how do they reproduce? That’s where bugs and birds get involved. Plants have co-evolved with insects to obtain pollination services by rewarding them with nutritious nectar. Likewise, plants have co-evolved with birds to distribute seeds by rewarding them with nutritious goodies surrounding seeds. Birds wouldn’t have seeds and fruit to eat without POLLINATING INSECTS, so here, I’m going to focus on pollination.

The survival of about 70% of our native flowering plants is dependent on insects for pollination. (And of course hummingbirds!) The remainder use the elements (wind, water) or vertebrates (bats, hummingbirds, reptiles).

When pollinating insects visit a typical flower for nectar, the flower’s strategy is to position the male anther so its sticky pollen gets stuck on their bodies. The insects end up carrying the pollen on their bodies to another flower on a different plant without realizing it. Once there, the female stigma is positioned so the pollen will be incidentally deposited on it to complete pollination! This cross-pollination results in plant reproduction of viable, genetically diverse seeds.

There are many strategies that plants have evolved, including some that are quite devious, to only encourage the insects capable of completing pollination. Some plants don’t even produce nectar. And some insects aren’t capable of completing pollination because they aren’t the right size, shape, or have a long enough tongue. Then there are insects that have direct interaction with pollen by eating it (beetles) or gathering and removing it to feed their larvae (female bees).

Coneflower with butterfly, wasp, and flower fly pollinators.
This coneflower attracted a butterfly, a wasp and a fly together.

What insect do you think of when someone says pollinator? If you said honeybee, you’d be in the majority. As birders, you can appreciate this analogy: Honeybees are to Bees as Chickens are to Birds. Huh? Honeybees, like chickens, are livestock that are farmed. They’re critical to pollinating our food supply (about 37% of global crops require pollination), but are not part of our native ecosystem. It’s still ok to like honeybees!

So who are our pollinators? Let’s take a closer look at the top insect groups.

Bees and a few Wasps (Hymenoptera)

Bees are our most important pollinators. Most bees are very hairy and produce a slight electrostatic charge that attracts sticky pollen. I love watching and listening to bumblebees “buzz” feed. This pollinating behavior, required by some plants to release pollen, results from a sonic vibration of the wings. A recent Pennsylvania State University inventory identified 437 bee species in PA.

Pollen is critical for bee reproduction. Females gather and provision pollen for their offspring in nests. Some native bees are pollen specialists requiring a specific plant for survival. Bees have evolved varied strategies to collect pollen. Female species with pollen sacs on their legs will transfer pollen to the sac to return to the nest. The Megachile family, including leaf cutter bees, have brush hairs under their abdomens that they drag over the flowers. Masked bees lack hairs and instead ingest pollen into a special internal organ.

This bumblebee was blasted in the face with pollen from buzz pollination.
The Megachile family females collect pollen under their abdomens.
Masked bees are tiny and resemble wasps.
Flower flies are important pollinators, but often mistaken as bees.

Flies (Diptera)

Did you know that chocolate is only pollinated by midges, a type of fly? Flies are responsible for about a third of all pollination services. They’re particularly important to flowers that bloom early in spring or late into fall, as well as in habitats like the arctic where bees are less active. Scientists are learning that bees move more frequently in the presence of flies, making them more efficient pollinators. Almost half of fly families visit flowers for nectar.

The most important pollinating fly family is Flower Flies (Hoverflies/ Syrphids). Many have a modified mouth part for sipping nectar from long, narrow flowers, and some are also striking mimics of bees or wasps. To separate Flower Flies from bees, look for stubby antennae, only 1 pair of wings, and larger eyes.

Long-horned Flower Beetles are often seen crawling between flowers instead of flying.

Beetles (Coleoptera)

Beetles were some of the first pollinators, having evolved with early flowering plants long before the bees appeared. They’re still essential pollinators today because of their huge numbers.

Unlike other pollinating families, most beetles don’t sip nectar. Instead, they chew and consume parts of the flower and plant. Some eat significant amounts of pollen and can be destructive. Beetles most frequently pollinate flat wide flower heads (like native hydrangeas) and big-flowered ancient plant flowers (like swamp magnolia).

Many pollinating beetles are common, beautiful, and easy to recognize, but species often lack common names. Pollinating beetle families in Pennsylvania include: soldier, blister, long-horned, checkered, tumbling flower, soft-winged flower, scarab, false blister, and rove. Flower Longhorns are one of my favorite beetle families. There are many species, and they have slender colorful or patterned bodies with long elegant antennae.

Pollination continues into the night, particularly by moths.

Butterflies and Moths (Lepidoptera)

As adults, many butterfly species are nectar feeders that are “incidental” pollinators. Those long legs position them above the flower, so their wing scales (they don’t have hair) don’t get covered in pollen. Pollen that gets stuck to their long tongues (proboscises), legs, and face – combined with frequent trips to flowers – is largely responsible for their pollination.

So, what about moths? Many of our day flying moths are pollinators. The most renowned locally is the Hummingbird Clearwing. To find night pollinators, shine a light on night blooming plants. A mass of Summersweet (Clethra alnifolia) shrub outside my front door attracts a wide variety of night visiting moth pollinators.

When looking at flowers, here are some tips to better appreciate their pollinators:

  • Observe pollen collection techniques. Do they “buzz”, crawl, or stand while feeding? Do they move quickly between flowers or hang out on one?
  • Look close for tiny insects. Some pollinators are smaller than ¼ inch.
  • Match flower shapes with pollinators. Flower types co-evolved with pollinator traits like tongue length and body shape.
  • Check nearby leaves and petals for insects grooming before flight.

Karen Campbell, is a Lehigh Valley Audubon board member and Certified Pollinator Steward. She shares her work on FocusOnNatives.com and Instagram. Karen provided the content and permission for use of her images for this article.