Bees & Pollinators, Insects

Can You Help our Most Effective Pollinator?

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By Silvia Strobl, Master Gardener

Pollinator insects – bees, wasps, beetles, flower flies, ants and butterflies–play an important role in the production of almost 75% of global food crops (FAO 2018). For example, only the tiny chocolate midge is able to pollinate flowers of the cacao tree and produce cacao pods! But bees, including native bees, are responsible for the biggest share at 35% of global food production (Ritchie 2021), including economically important commercial crops such as apples and blueberries! 

Bees are such effective pollinators because of the specialized hairs and pollen carrying structures on their legs that enable them to gather and transport pollen. The vast majority of bee pollinators are wild, including over 20,000 species of native bees worldwide and 400 species in North America. In natural ecosystems, bees visit the most plants and have the most interactions with flowers as compared to other insect pollinators (Radar et al. 2020). 

Bees have specialized hairs and pollen carrying structures as seen in the large filled pollen sacs of this Common Eastern Bumble Bee (Bombus impatiens) collecting nectar and pollen on native Shrubby St. John’s-wort (Hypericum prolificum). 

I enjoy photographing the busy native Bumble Bees in my garden that collect pollen from a wide variety of flowers, often late into summer evenings. Here are a few species that you may see, too. 

This Yellow-banded Bumblebee (B. terricola) with its distinct yellow and black abdominal band pattern is collecting nectar and pollen from the native Virginia Mountain Mint (Pycnanthemum virginianum). This species is ranked as “Special Concern” in Ontario, meaning it is not endangered or threatened, but may become threatened or endangered due to a combination of biological characteristics and identified threats. Its nests are often underground in abandoned rodent burrows or decomposing logs.
Here the Perplexing Bumblebee (B. perplexus) is collecting nectar and pollen from native Anise Hyssop (Agastache foeniculum). As its name suggests, this bumble bee can be rather perplexing to identify! As it’s not very common, rather little is known about it.
The Brown-belted (B. griseocollis) is a short-tongued Bumble Bee and native Butterfly Milkweed (Asclepsis tuberosa) is just one of the flowers it prefers. It is one of the most abundant and widespread bumble bees in northeast North America.

You can find excellent guides to help you identify the bumble bees in your garden here and you can learn more about native bees in this excellent publication.

Sadly, all pollinators are experiencing alarming declines due to habitat loss, pesticide exposure, invasive species, parasites/diseases and climate change. One study found that when compared to 125 years ago, 30% of plant:pollinator associations have been lost (Mathiasson and Rehan 2020).  Five Bumble Bee species, American, Gypsy Cuckoo, Rusty-patched, Suckley’s Cuckoo, and Yellow-banded, are currently listed as Endangered, Threatened or Special Concern in Ontario.

Gardeners Can Help!

Gardeners can help native bees by creating habitat, providing floral resources and maintaining a pesticide-free garden:

  1. Nesting & overwintering habitat 
  • Most native bees (60-70%) nest in the ground. Use a thin layer of mulch and avoid using landscape paper/fabric which prevents bees from making a nest in the ground.
  • Leave some scrubby areas in your garden for bees
  • For the 30-40% of stem nesting bees, cut back perennials later in spring leaving those with hollow stems at varying lengths (20 to 60 cm) as shown in this excellent guide. If you do cut, leave the bottom 20 cm in place, bundle the cut stems, and place them in your garden.
An entrance hole of a bumble bee ground nest in a patch of native Pussy Toes (Antennaria neglecta) in the author’s garden.
  1. Floral resources
  • Plant a diversity of native and non-native plants to have continuous blooms, and sources of nectar and pollen, from early spring to late fall
  • Include at least one native early spring blooming shrub or tree (e.g., willow, redbud, cherry) for emerging queen bees
  1. Pesticide-free habitat
  • Avoid using pesticides. Recent research from the University of Guelph has shown that ground-nesting native bees experience reduced pollen collection, induced hyperactivity or decreased number of offspring emerging per nest even when so-called “bee-safe” pesticides were used (Rondreau and Raine 2024).

Your habitat restoration efforts, especially adding native flowering plants, will go a long way to helping our native bee pollinators, and also our food security.

References

FAO. 2018. Why bees matter. https://openknowledge.fao.org/server/api/core/bitstreams/0f47dba8-ab04-4968-a2bc-8a9c06218653/content

Mathiasson, M.E. and S. M. Rehan. 2020. Wild bee declines linked to plant-pollinator network changes and plant species introductions. Insect Conservation & Diversity. https://resjournals.onlinelibrary.wiley.com/doi/abs/10.1111/icad.12429

Radar, R., S.A. Cunningham, B.G, Howlett, and D.W. Inouye. 2020. Non-bee insects as Visitors and Pollinators of Crops: Biology, Ecology, and Management. Annual Reviews Vol. 65:391-407. https://www.annualreviews.org/content/journals/10.1146/annurev-ento-011019-025055

Ritchie, H. 2021. How much of the world’s food production is dependent on pollinators? Retrieved from: https://ourworldindata.org/pollinator-dependence

Rondreau, S. and N.E. Raine. 2024. Single and combined exposure to ‘bee safe’ pesticides alter behaviour and offspring production in a ground-nesting solitary bee (Xenoglossa pruinosa). Proceedings of the Royal Society Biological Sciences. https://royalsocietypublishing.org/doi/10.1098/rspb.2023.2939

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