a green sweat bee
What are wild pollinators? 

The “pollinator crisis” has received a lot of media attention over the past decade, and most people are aware that "pollinators" are in trouble. Much of this attention has focused on the collapse of non-native, managed honey bee populations due to their tremendous economic importance as crop pollinators for human agriculture. 

 

However, the sharp decline of many of our native pollinator species, though less recognized, is an ecological crisis of similar magnitude that also deserves our attention. These insects, birds, and mammals provide vital ecological services that are imperative for the proper functioning and resilience of our local ecosystems, especially in the face of climate change. By not recognizing the role our actions play in their decline, we ignore the need to protect these diverse and critical species.  

Why are  Pollinators in Crisis?
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Many pollinators around the world, including in Massachusetts, are in crisis. Although the exact mechanisms causing their decline are not fully understood, several factors are thought to play major roles. The good news is that we can mitigate many of these things, especially in our private yards through responsible land stewardship practices, that will have   immediate, positive impact.

Climate Change

Milder winters and hotter summers directly impact the survival of both pollinators and native plants. Pollinator systems have co-evolved so that pollinators and the native plants they depend on for food and shelter have become desynchronized, impacting native pollinators and the pollination success of native plants.

Habitat Loss

Habitat loss contributes to pollinator decline through fragmentation of available nesting sites and food sources. As native vegetation is replaced by roadways, manicured lawns (“green deserts”), crops, and gardens containing ornamental plants, pollinators lose the connectivity of resources that ensure their survival.

Pesticide Use

Although initially thought to be a “safe” insecticide that only targeted “pests”, recent research suggests that neonicitinoids, or “neonics”, (a class of insecticides that are widely used) may be harmful not only to native insects, including pollinators, but adversely affect human health, as well.

Disease

Weakened by pesticide exposure, reduced nutrition, and loss of habitat, pollinators have become more susceptible to new pests and diseases, including those introduced from foreign managed honeybee colonies imported for crop pollination services.

Invasive Species

Introduced plant species can destroy delicate ecosystem balances by outcompeting native plants, reducing the diversity, and eliminating food and shelter that native pollinators require for survival. Likewise, invasive insect species can compete with native pollinators for limited resources.

Why Does This Matter?

Massachusetts is home to thousands of native pollinator insect species. Many species are declining or have become extinct, although some have increased in abundance. In Massachusetts alone, 3 of the 9 remaining bumblebee species are at risk of extinction within the next decade. 

 

Wild pollinating species, primarily insects, represent a vast functional diversity. The majority of these animals are "generalists," meaning they depend on a variety of different plant types for pollen and nectar. However, many pollinators are "specialists" relying on a single plant species (or a small number of highly-related plants) for survival. 

Meet the Pollinators
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What about honey bees?

Although one of the most recognizable pollinators, honey bees are a single introduced species, brought to America by European settlers to provide honey and beeswax 

The contributions and challenges of managed honeybees are well documented in an agricultural context

Honey bees are highly social and, unlike native bees, can be very aggressive when protecting their hives

Photo credits: Native bee- Nicole Mordecai; Fly- Sarah Maas Scheuplein;  Butterfly- Nicole Mordecai; Moth- Victoria Huber; Beetle- Rbreidbrown, CC BY-SA 4.0, via Wikimedia Commons

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Native Bees

Bumblebees, the most recognizable native bee species, are social and live in small hives underground

Bees are extremely efficient pollinators

Other types of native bees include carpenter, sweat, mason, digger, miner, leafcutter

Most native bees (~90%) are solitary and nest in cavities or in the ground

~75% of native bees are generalists, meaning that they visit many types of flowers

Different bees have different tongue lengths (long, medium, or short), so prefer different types and shapes of flowers depending on their anatomy

 

Incorporating a wide variety of flower shapes, colors, and sizes will attract many different native bee species

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Beetles

Thought to be among the most ancient pollinators, beetles have been pollinating certain plants including magnolias, spicebushes, and water lilies for ~200 million years

Beetles appear to prefer more open flowers with strong, fruity, or rotten scents, usually white or green in color

Image by Zdeněk Macháček

Hummingbirds

The Ruby-throated Hummingbird is the only bird pollinator in the eastern US

Ruby-throated hummingbirds overwinter in Central Mexico and return to breeding grounds in the eastern US and Canada every spring

Hummingbirds are drawn to red tubular shaped flowers that match the shape of their bill (for example, Cardinal Flower, Wild Red Columbine, and Trumpet Vine)  

Image by Duncan Sanchez

Wasps

Wasps are mostly "incidental" pollinators, passively carrying pollen from flower to flower as they nectar instead of actively collecting it, like bees. They have less body hairs so are less efficient at pollination since the pollen doesn't stick to them well

Wasps are beneficial insects, performing essential ecosystem services like managing pest insect populations through predation

Social wasps can be aggressive when threatened, but solitary wasps (the large majority of wasp species) rarely sting and should be left in place when possible

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Butterflies

Butterflies are some of the showiest garden visitors and rely mostly on nectar-producing flowers

Some butterfly species remain local throughout their entire lifecycle, while many other species migrate, returning to northern breeding grounds in spring or summer 

 

The most famous migratory butterfly species, the Monarch, has declined by more than 80% in the past 20 years

Butterflies prefer brightly colored, open flowers such as Joe-Pye weeds, goldenrod, and milkweed (also the host plant for Monarchs)

Image by Zdeněk Macháček

Bats

Although there are no flowers that rely on bats for pollination in Massachusetts, bats are necessary for pollination of certain flowers such as many fruits, agave, and cacti in the Southwestern U.S.

Much like moths, bats also rely on flowers that are open at night, and color is not as important

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Flies

Flies are a diverse group of insects and are important pollinators

Flies are often generalists, pollinating many different flower species

Some fly species resemble bees or wasps but only have one pair of wings instead of two

Larvae of many hoverflies are beneficial and prey on aphids

 

Flies seem to prefer dark brown or purple flowers that smell like rotting flesh (e.g. skunk cabbage)

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Moths

Closely related to butterflies but mostly active at night (notable exception is the hummingbird moth, shown above)

There are many more native moth species than butterflies

Moths visit many of the same flowers as butterflies, although flower color is less important and flowers need to be open at night