The Pollination

of Native PlantsHeather Holm

Overview

Types of Insect Pollinators

Pollination

Access to Floral Resources

Flower Features & Attractants

Flower Development & Presentation of Resources

Green Sweat Bee Agapostemon sp.

Flies

Bees Social Wasps

BeetlesMothsButterflies

Solitary Wasps

Types of Insect Pollinators

Over 4000 species of bees in North America

300+ species of bees in Minnesota

Bees

Types of Insect Pollinators

Small Carpenter Bee Ceratina sp.

Bees - Common Genera in Minnesota

Mining Bees Andrena spp.

Long-Horned Bees Melissodes spp.

Mason Bees Osmia spp.

Small Carpenter Bees Ceratina spp.

Leafcutter Bees Megachile spp.

Small Resin Bees Heriades spp.

Carder Bees Anthidium spp.

Digger Bees Anthophora spp.

Types of Insect Pollinators

Bees - Common Genera in Minnesota

Sweat Bees Halictus spp.

Cellophane Bees Colletes spp.

Yellow-Faced Bees Hylaeus spp.

Small Sweat Bees Lasioglossum spp.

Green Sweat Bees Agapostemon spp.

Sweat Bees Augochlora spp.

Sweat Bees Augochlorella spp.

Types of Insect Pollinators

Bees - Common Genera in Minnesota

Cuckoo Bees Nomada spp.

Cuckoo Bees Triepeolus spp.

Cuckoo Bees Sphecodes spp.

Cuckoo Bees Coelioxys spp.

Types of Insect Pollinators

Bumble Bees, Bombus spp.

18 species in Minnesota

Types of Insect Pollinators

Bald-Faced Hornets Dolichovespula spp.

Paper nests in trees

Yellowjackets Vespula spp.

Paper nests in trees or in the ground

Paper Wasps Polistes spp.

Open paper nests on horizontal surfaces, tree limbs, house soffits

Social Wasps - Colony (Paper Nests)

Visit Flowers to Feed on Nectar

Types of Insect Pollinators

Ground Nesting Colonies Aggressive

Picnic Visitors

Attracted to fruit, pop, meat

MOST insect stings are caused by social wasps NOT BEES

CarnivoresFlower Visitors Docile

Yellowjacket Wasps

Types of Insect Pollinators

Construct Solitary Nests NOT Aggressive

Great Golden Digger Wasps Sphex ichneumoneus

Great Black Wasp Sphex pensylvanicus

Mason Wasps Euodynerus spp.

Solitary Wasps

Types of Insect Pollinators

Potter Wasps Eumenes spp.

Thread-Waisted Wasps Ammophila spp.

Grass-Carrying Wasps Isodontia spp.

Solitary Wasps = Beneficial InsectsHunt crickets, grasshoppers, katydids, sawfly larvae, caterpillars, beetles and bugs

Types of Insect Pollinators

Long Mouthparts = Access to Deep Tubular Flowers

Visit Flowers to Feed on NectarButterflies and Moths

Types of Insect Pollinators

Large butterflies pick up pollen on their wings

Small butterflies and moths pick

up pollen on their head and

mouthparts

Butterflies prefer flowers with a large landing platform

Butterflies and Moths

Types of Insect Pollinators

Visit Flowers to Feedon Nectar and Pollen

Soldier BeetlesChauliognathus spp.

Beetles

Types of Insect Pollinators

Long-Horned Beetles Cerambycidae Family

Beneficial Insect Some adults and most larvae are predators of aphids

Syrphid Flies (Flower Flies) Family Syrphidae The larvae of many syrphid flies feed on aphids

Flies

Types of Insect Pollinators Visit Flowers to Feedon Nectar and Pollen

Beneficial Insect

Bee Mimics

Bumble Bee Mimics

Wasp Mimics

Bee Flies Family Bombyliidae

Flies

Types of Insect Pollinators

Many have long, modified mouthparts

Tachinid FliesFamily Tachinidae

FLOWER = Food/Nesting MaterialsNectar • Pollen • Resin • Oil

INSECT = Transfers Pollento Other Plants ~ Pollination

Mutualistic ExchangePollination

Tongue Length

Bumble Bees Bombus spp.

Butterflies and Moths

Access to Floral Resources

Long Tongued

Yellow-Faced Bees Hylaeus spp.

Short Tongued

Syrphid FliesFamily Syrphidae

Size

Small Able to crawl into corollas of different widths to feed on resources

Medium - Large Restricted by tongue length & flower access

Access to Floral Resources

Easy Access

Composite ‘Daisy-Like’ Flowers

Azure Aster Symphyotrichum oolentangiense

Floral Features

Bilabiate

Smooth Beard Tongue Penstemon digitalis

Access More Restrictive

Flower Forms - Simple to Complex

ClosedRequires a bee strong enough to pry flower open

Bottle Gentian Gentiana andrewsii

Access Very Restrictive

Strength White Turtlehead, Chelone glabra

Access to Floral Resources

Pollen Basket (Corbicula)

Pollen Collection on the Hind Leg

Pollen Collection on the Abdomen

Bumble Bees & Honey Bees

Bees in the Leafcutter Family (Megachilidae)

Most other bees

Only female bees have pollen-collecting structures

Pollen Collection - Bees

Floral Resources

Swamp Milkweed Asclepias incarnata

Pollen Collection - Packaged Pollen

Floral Resources

Pollen Feeding - Bees, Flies, Beetles

Prairie Phlox, Phlox pilosa

Jacob’s Ladder Polemonium reptans

New England Aster Symphyotrichum novae-angliae

Floral Resources

Pollen is a source of protein

Solomon’s Seal Polygonatum biflorum

Prairie Smoke Geum triflorum

Buzz PollinationFloral Resources

Attractants

Nectar Guides

Stripes, spots or color contrasts on the flower

Prairie Phlox Phlox pilosa

Wild Petunia Ruellia humilis

Floral Resources

New England Aster Symphyotrichum novae-angliae

American Pasqueflower Anemone patens

Flower Color & Color Contrast

Flower Color & Color Contrast

Yellow petals and stamens only visual attractant

Bees do not ‘see’ red

A human’s view of black-eyed susan flowers

A bee’s view of black-eyed susan flowers

Attractants

Wild Columbine Aquilegia canadensis

Black-Eyed Susan Rudbeckia hirta

Floral Resources

Presentation of Resources

Sequential Development

Male Phase Female Phase = Protandrous

Wild GeraniumGeranium maculatum

Offset development of reproductive flower parts limits self-pollination

Flower Development

Sequential Development - Influence of Pollinator Activity

Wild GeraniumGeranium maculatum

Mason BeesOsmia spp.Collect Pollen

Small Carpenter BeesCeratina spp.Feed on Nectar

Syrphid FliesPipiza spp.Feed on Pollen

Presentation of ResourcesFlower Development

Self-compatible

Self-pollinates around the third day of flower opening

Flowers during fluctuating temperatures and potentially low pollinator activity

Bloodroot Sanguinaria canadensis

Sequential Development - Self-Pollinating Flowers

Presentation of ResourcesFlower Development

Sequential Development

Female Phase Male Phase = Protogynous

American PasqueflowerAnemone patens

Low nectar reward

Flowers track sun throughout the day creating a warm place for pollinators to forage

Presentation of ResourcesFlower Development

Canada Tick Trefoil Desmodium canadense

Keel Depressed Pollen Forcibly Ejected

Flower Activated

Pollen Presentation

Presentation of ResourcesFlower Development

Leafcutter Bee Megachile sp.

Pollen Presentation

Presentation of ResourcesFlower Development

Harebell Campanula rotundifolia

Male Phase Female Phase = Protandrous

Pollinators visit for pollen and nectar

Pollen Presentation

Presentation of ResourcesFlower Development Harebell

Campanula rotundifolia

Male Phase Female Phase = Protandrous

Pollen is shed from anthers and drops into the bottom of the flower

As the style elongates, hairs pick up the pollen grains

Bees feed on pollen presented on the style

Pollen Presentation

Presentation of ResourcesFlower Development Harebell

Campanula rotundifolia

Leafcutter bees collect/pick up pollen on their abdomen as they forage for nectar

Pollen Presentation

Presentation of ResourcesFlower Development

Harebell Campanula rotundifolia

Hairs eventually retract, pollen falls off and the stigma becomes receptive

Female Phase

Pollinatorsvisit for nectar

Presentation of ResourcesFlower Development

Nectar Production/Nectary Location- Influence on Foraging Behavior

Wild White Indigo Baptisia lactea

Flowers develop from the bottom of the raceme upward

Nectar production peaks during the female (pistillate) phase

Male Phase Female Phase = Protandrous

Presentation of ResourcesFlower Development

Nectar Production/Nectary Location - Influence on Foraging Behavior

Wild White Indigo Baptisia lactea

Flowers primarily visited by queen bumble bees in early spring

Bumble bees land on the lowest open flowers on the raceme

Lowest flowers are in the female phase producing more nectar

Male Phase Female Phase = Protandrous

Downy Yellow Violet Viola pubescens

Enter Violets Upside Down to Feed on Nectar

Illustration redrawn from: Beattie, A. J. (1974). Floral evolution in Viola. Annals of the Missouri Botanical Garden, 781-793.

Presentation of ResourcesFlower Development Nectar Production/Nectary Location

Influence on Foraging Behavior

Presentation of ResourcesFlower Development

Nectar Production/Nectary Location- Influence on Foraging Behavior

Prairie Phlox Phlox pilosa

Nectary at the base of the flower corollaAnthers staggered - 2 near opening, 2 belowAnthers shed pollen first (protandrous)

Presentation of ResourcesFlower Development

Nectar Production/Nectary Location- Influence on Foraging BehaviorPollen Presentation

Prairie Phlox Phlox pilosa

Initial visits after flowers open are by pollen-foraging pollinators

Presentation of ResourcesFlower Development

Nectar Production/Nectary Location- Influence on Foraging BehaviorPollen Presentation

Prairie Phlox Phlox pilosa

Butterflies and moths are the most effective and primary pollinators

Flowers are self-incompatible (require cross-pollination)

Provide a Variety of Flowering Native

Plants That Overlap Through The Season

Leave Areas of Bare Soil For Ground Nesting Bee Species

Place/bundle hollow plants stems in the landscape for Cavity-Nesting Pollinators

Leave Standing Tree Snags, Old Potter Wasp Nests, Standing Hollow Stems

Do not use pesticides.

1Provide Larval Host Plants for Butterflies & Moths

Talk to Your Neighbors or friends about the importance of pollinators

Create New Habitat for pollinators and remove invasive plants

Use Straight Native Plant Species

Plant breeding can cause flowers to

lose fragrance, nectar, pollen &

bee accessibility

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Do Not Disturb Existing Nesting

Sites in your landscape

Top 10 Things YOU can do for Pollinators