Pollinator Conservation Biocontrol: Bees

rusty patch bumble bee bee balm

More than half of North America's wild bees are in decline, and 1 in 4 at risk of extinction. Native bees, honey bees, wasps and other pollinators are keystone species and provide pollination services for over 30 percent of human food.  The best crop pollinators are a combination of honey bees and wild bees.

Fruits and seeds derived from insect pollination are also a major part of the diet of birds and mammals ranging from red-backed voles to grizzly bears. There are an estimated 460 wild bees in Minnesota. The rusty patched bumble bee (Bombus affinis) was once abundant but is now a federally endangered species. In addition, Minnesota has 8 state-listed endangered pollinator species, 1 threatened, 10 species of special concern and 19 non-listed in greatest conservation need. 

Bumble bees and other pollinators need high quality habitat to survive. For the endangered rusty patched bumble bee, urban habitats can be just as important as parks or rural landscapes. Keeping areas pesticide free is important for habitat quality and for the recovery of the rusty patched bumble bee.

Principles of Bee Conservation

  • Habitat Conservation is a priority for safeguarding bees. Unfortunately, only 1% of original prairie habitat is left in Minnesota. Many species depend on this type of habitat and the species of plants that inhabit it. If we can increase native prairie habitat in urban and rural areas, the bees will come along with it.
  • Season-long shelter: Leave some sandy open areas for ground nesting bees. Brush, leaf and mulch piles, logs, and overgrown areas provide safe places to overwinter or hibernate. Wait until late spring (May) to clean backyard gardens for hibernating bees. Many species of bees overwinter in hollowed out stiff plant stems. 
  • Food: Plant diverse flowers that bloom from early spring through fall. Pollinators collect nectar and pollen from a variety of flowering plants including native plants, heirloom garden plants, trees, weeds and crops. In your yard, plant heirloom and native species such as salvia and milkweed, shrubs like ninebark and pussy willow, and flowering trees like basswood and plum. 
  • Avoiding the use of pesticides is one of the most important conservation decisions we can make. Pesticide drift and contamination from industrial agriculture is a major contributer to butterfly die offs.

Steps to Conserve Bees

  1. Provide nectar plants that bees prefer. Plants such as yellow sunflower, black-eyed susans and goldenrods, pink joe-pye weed and fireweed, red bee balm/bergamot, and Mexican sunflower, purple coneflower, verbena, wild asters, ironweed and tall buddleia provide plentiful color. 
  2. Include multiple habitats for different needs. Leave some sandy open areas for ground nesting bees. Brush, leaf and mulch piles, logs, and overgrown areas provide safe places to overwinter or hibernate. Wait until late spring (May) to clean backyard gardens for hibernating bees. Many species of bees overwinter in hollowed out stiff plant stems. Use biodiversity as a guide to include a variety of water, protection, sun, flowers, grasses, shrubs and trees.
  3. Reduce or stop using pesticides. Instead, accept some plant damage, build biodiversity and soil health for natural pest control. If pesticides are necessary, use more benign spot treatments and alternative control methods such as oils, soaps, and microbial insecticides such as Bacillus thuringiensis (Bt).  
  4. Use integrated pest management (IPM) to control insects and diseases:
    • When choosing plants, pick naturally resistant plants.
    • Inspect and monitor your plants' health on a regular basis, before problems are out of control.
    • Instead of routinely spraying for insects, spot treat problems with soft pesticides such as insecticidal soaps, oils, and biorational products such as spinosad. 
    • Adopt biorational practices that use naturally occurring biological control agents, such as parasitoids and predatory insects.
  5. Plant both annual and perennial plants for butterflies. Some plants, shrubs or trees produce nectar AND pollen, others only produce one or the other. Some plants and trees are also host plants for larvae and others are not. Remember to source plants and trees that have NOT been treated with pesticides. Pesticides harm butterflies, moths, pollinators and other non-target beneficial insects.

1. Family Colletidae (common name: cellophane or polyester bee)

Colletes spp. Black and white banding on abdomen Size: Small - medium, 7- 15 mm (0.3 - 0.6 in) Head: Hairy head and thorax, heart shaped face (strongly converging eyes) Tongue: Short, 1 - 3 mm (0.4 - 0.12 in), two lobed Flight distance: 150 m (500 ft) Nest: Ground, often near water, dense aggregations in sandy, loamy soil, loam, clay loam with nest lining of Dufour's gland secretion of cellophane, brushed on with glossa Pollen collection: Scopae, upper hind legs and thorax

Colletes spp. (Steve Scott, BugGuide.net)
Colletes spp. carrying pollen (Aaron Schusteff, BugGuide.net)
Colletes spp. ground nest (Aaron Schusteff, BugGuide.net)

2. Family Colletidae (common name: yellow-faced bee)

Hylaeus spp. Black with yellow markings Size: Small, 5 - 7 mm (0.2 – 0.3 in) Tongue: Short, 1 - 2 mm (0.04 - 0.07 in) hairless, bi-lobed Nest: Preexisting cavities: stems or twigs with cellophane-like material, brushed on with glossa Pollen collection: Crop, no pollen-collecting scopae

Hylaeus spp. (Kurt Hennige, BugGuide.net)
Hylaeus spp. twig nest (George Cordiner, BugGuide.net)
Hylaeus spp. collecting pollen (Heather Holm)
Andrena spp. carrying pollen (iNaturalist)
Andrena spp. ground nest (Libby & Rick Avis)
tawny mining bee
Milwaukee mining bee (Laurie schneider)
Calliopsis spp. (Paul Scharf, BugGuide)
Calliopsis spp. carrying pollen (Hartmut Wisch, BugGuide)
mining bee inaturalist
Calliopsis spp., note green eye (Odophile/iNaturalist)
Halictus spp. (Sarah Christopherson, BugGuide)
Halictus spp. carrying pollen (Molly Jacobson, BugGuide)
Halictus spp. ground nest, J. Gibbs, BugGuide
Lasioglossum spp. (Gary McDonald, BugGuide)
Lasioglossum spp. carrying pollen (Kurt Hennige, BugGuide)
Lasioglossum spp. coming out of a nest in a log (Heather Holm)
Agapostemon spp. (Peter Bryant, BugGuide)
Agapostemon spp. carrying pollen (Betsy Betros, BugGuide)
Agapostemon ground nest (Diane Wilson, BugGuide)
Sphecodes spp. male (Heather Holm)
Sphecodes spp. female (Heather Holm)
Sphecodes spp. female investigating Halictus rubicundus nests (Heather Holm)
Augochlora spp. female (Heather Holm)
Augochlora spp. nest in log (Heather Holm)
Augochlora spp. female covered in pollen (Heather Holm)
Augochlorella spp. female feeding on nectar (Heather Holm)
Augochlorella female with scopae covered in pollen, photo: Heather Holm
Augochlorella spp. female with scopae covered in pollen (Heather Holm)
Augochlorella spp. female (Heather Holm)
Osmia spp. (Sam Houston, BugGuide)
Osmia spp. gathering mud (Jonathan Wright, BugGuide)
Osmia spp. carrying pollen (Diane Wilson, BugGuide)
Megachile spp. female (Heather Holm)
Megachile spp. in stem nest (Heather Holm)
Megachile spp. leaf nest closure (Heather Holm)
Heriades spp. male (Heather Holm)
Heriades spp. female (Heather Holm)
Heriades spp. nest in drilled wood (Paul Heiple, BugGuide)

14. Family Megachilidae (common name: mason bee)

Hoplitis spp. Black or metallic (western species), slender, robust, hairy face Size: Small to medium 5 - 15 mm (0. - 0.6 in) Nest: Preexisting cavities (pithy stems, wood, old nests in soil or mud nests with nest) Pollen collection: Abdominal scopae

Hoplitis spp. (Dave Beaudette, BugGuide)
Hoplitis spp. female (Heather Holm)
Hoplitis spp. male (Chelsey Ritner, Bugwood.org)
Coelioxys spp. female (Heather Holm)
Coelioxys spp. female (Heather Holm)
Male and female Coelioxys spp. (Heather Holm)
Anthidium spp. (T. Stone, BugGuide)
Anthidium spp. carrying pollen (Rich Schilk, BugGuide)
Anthidium spp. nest (Don Patterson, BugGuide)
Bombus spp. worker (Heather Holm)
Bombus spp. queen (Heather Holm)
Bombus spp. nest in a log (Heather Holm)
Anthophora spp. (Diane Wilson, BugGuide)
Anthophora spp. carrying pollen (Harmut Wisch, BugGuide)
Anthophora spp. nest (Loren Padelford, BugGuide)
Nomada spp. male (Heather Holm)
Nomada spp. female emerging from an Andrena nest (Heather Holm)
Nomada spp. female near Andrena nest (Heather Holm)

20. Family Apidae (common name: cuckoo bee)

Triepeolus spp. Black with yellow or white markings, very short hair, appearing hairless Size: Medium, 3 - 15 mm (0.1 - 0.2 in) Tongue: Medium, 4 - 5 mm (0.1 – 0.2 in) Nest: Cleptoparasite of digger bees and Andrenids (lays eggs in other bees' nests) Pollen Collection: None

Triepeolus spp. male (Alan Smith-Pardo, Bugwood.org)
Triepeolus spp. female (Alan Smith-Pardo, Bugwood.org)
Triepeolus spp. (Heather Holm)

21. Family Apidae (common name: small carpenter bee)

Ceratina spp. Blue, black, green, metallic with cylindrical abdomen, sparsely haired, shiny, often white (or yellow) patch on face Size: Small - medium, 3 - 15 mm (0.1 - 0.6 in) Tongue: Medium, 5 - 9 mm (0.2 - 0.35 in) Nest: Pithy stems, wood in vertical or angled nest orientation with nest divisions of pith and saliva Flight Distance 180 m (200 yd) Pollen Collection: Scopae hind legs

Ceratina spp. (H. Go, BugGuide)
Ceratina spp. nest in wood (Pam Phillips. BugGuide)
Ceratina spp. feeding on nectar (L. Schneider)

22. Family Apidae (common name: long-horned bee)

Melissodes spp. Robust and hairy, often bands on abdomen in the middle of the abdominal segments Size: Small - medium, 7 - 18 mm (0.3 - 0.7 in) Males: long antennae Tongue: Medium - long Nest: Ground nest with lining of wax-like substance Pollen Collection: long scopae on hind legs

Melissodes spp. males (Heather Holm)
Melissodes spp. female (Heather Holm)
Melissodes spp. female with pollen (Heather Holm)

23. Family Apidae (common name: large carpenter bee)

Xylocopa spp. Black with yellow hairs, bumble bee-like with robust, hairy thorax, shiny black abdomen Size: Large 13 - 30 mm (0.5 - 1.25 in) Tongue: Medium - long Nest: Excavated with mandibles in wood and plant stems and nest lining of sawdust (plant stems) Flight Distance: 1.6 km (1 mi) Pollen Collection: Scopae on hind legs

Xylocopa spp. (JoAnn Poe-McGavin, BugGuide)
Xylocopa spp. nest in wood (T. Gilliam, BugGuide)
Xylocopa spp. male (Heather Holm)

24. Family Apidae (common name: honey bee)

Apis mellifera Black with golden hairs and moderately hairy, long abdomen with black or gold stripes, hairy eyes Size: Medium, 10 - 15 mm (0.4 - 0.6 in) Tongue (worker): 5 - 8 mm (0.2 - 0.3 in) Nest: Social, colony mostly in man-made managed wood equipment; some feral hives in tree cavities Nest materials: Wax hexagonal cells Flight Distance 3.2 km (2 mi) Pollen Collection: Pollen baskets hind legs (corbiculae)

Apis mellifera (David Cappaert, Bugwood.org)
Apis mellifera with pollen (Dennis Riggs, Bugwood.org)
Honey bee swarm (David Cappeart, Bugwood.org)