On feeding hungry monarchs

A migrating monarch feeding on seaside goldenrod in Gloucester, MA. PC: Rachael Bonoan.

Fall is a time for migration in the North, as animals flee the bitter cold of winter in favor of warmer regions. If you’ve been outside in New England in the past few weeks, you’ve probably been in the presence of these migrants. Birds are some of the best known long-distance migrants, but plenty of insect pollinators embark on similarly stunning journeys each fall, in spite of their diminutive size. Some are inconspicuous and elusive, like the various species of hover fly whose migration through our region has only been recorded a few times in the past hundred years; others, like the monarch butterfly, are beloved signs of the closing of summer.

Each fall, millions of these large orange and black butterflies form a remarkable caravan, as monarchs from breeding grounds across a range that stretches as far north as Nova Scotia embark on the long flight to the overwintering grounds in central Mexico. These migratory monarchs need to reach dwindling undisturbed patches of oyamel fir forest, where they spend much of the cool winter perched in massive clumps on the trees, largely quiescent. There they wait for warmer temperatures that signal the arrival of Spring, when they can depart and gradually begin their multi-generational recolonization of the breeding range.

Surviving the 3000+ miles of flight and the subsequent months of cool winter in Mexico requires energy, and lots of it. The butterflies – weighing about a fifth of a penny – bulk up on nectar by gorging for hours on fall-blooming flowers. So efficient are their digestive systems that it’s thought that the sugars in the nectar can be converted into energy-rich fat stored in a special organ in a matter of minutes. Monarchs most likely need to more than double their regular fat stores during migration in order to survive the winter, meaning that stunningly, these butterflies actually gain weight during their multi-thousand-mile-journey. 

Two migrating monarchs on an aster species (Symphyotrichum sp.). In the fall, males and females are non-reproductive; they happily feed on the same plants and often roost together during migration. PC: Rachael Bonoan

You may have heard that monarch butterfly populations have suffered steep declines in recent years, with most estimates putting the losses in the Eastern population over 80%. A broad set of human actions have conspired against the monarchs, including deforestation in Mexico and agricultural herbicide use in the Midwest. Recently, ecologists have raised the specter of a third challenge: increased mortality during migration.

Migration is a dangerous undertaking, and biologists speculate that perhaps as many as 95% of monarchs attempting to migrate perish each year. As meadows and prairies have been converted to asphalt and crops, native grassland habitats that support large numbers of fall-blooming flowers are a dwindling commodity. Some ecologists posit that a lack of nectar along the migration route could be leading to starvation during the flight or in the quiescent overwintering period.

This is where we come in. Through planting gardens that can continue producing flowers all the way through October, we can provide valuable resources not just for monarchs but for all the other pollinators that are still flying. Surviving and thriving at this time of year in New England can be a tenuous proposition for animals that eat nectar and pollen: nighttime temperatures flirt with freezing and many of the flowering plants in our region have already gone to seed or begun senescing by September. In a summer with a drought like the one we’ve had in Massachusetts this year, wildflower outlooks can be even grimmer by the time October swings around. 

But where there is a tenuous situation, there is also an opportunity for our interventions to make a bigger difference. Much of the land in New England would, given the chance, burst into late-fall bloom every year in a riot of goldenrods and asters, pumping out nectar and pollen through until frost.  These native, pollinator-friendly species are conveniently often exceedingly drought-tolerant and some grow aggressively when given the chance, like the goldenrod species in the picture below:

A vacant lot in Rhode Island, September 2020, brimming with goldenrod. PC: Atticus Murphy.

Crucially, these patches can arise in the middle of neighborhoods on vacant lots or road verges, providing unexpected oases for fall-flying insects. Likewise, by carefully planning gardens that bloom continuously until the end of September, gardeners can provide nectar not only for migrating monarchs, but the hundreds of other pollinator species that require pollen during the fall. 

Adding autumn-blooming flowers amounts to starting a food bank for pollinators like monarchs, and by planting easy-to-grow native perennials like goldenrods and asters, the food bank will return every year, essentially for free! Migration is hard enough without pesky human interference; let’s try and help these iconic butterflies along their way, if we can.

Urban Boston Fall Pollinator BioBlitz!

This weekend, September 26-27, 2020, join TPI for a fall pollinator bioblitz! If you live in the city around Boston (east of I-95) get out during the weekend to observe pollinators—bees, butterflies, hover flies, wasps, and beetles—and post your sightings to iNaturalist. There will be so many insects to see, including monarch butterflies, bumble bees, paper wasps, goldenrod beetles, and more! If you’re not familiar with iNaturalist, see this guide for getting started.

During the bioblitz, TPI biologists will be scouring the flowers in our gardens on the Tufts University Medford-Somerville campus. We hope you’ll get out in your yard or neighborhood to look for pollinating insects, too. Your participation in this bioblitz will help TPI biologist better understand how gardens support pollinators in the city.

Never participated in a bioblitz before? Here are some tips to get you started:

Why you should thank a bee for your apple

Fall is approaching fast and that means one thing: apple picking season! If you’re from the Northeast, apple picking may have been a staple for you growing up. I know for me it was, and I would get particularly excited about my mom’s homemade apple crisp.

Apple picking is a great activity that can be done socially distanced! Image Credit: Sylvie Finn

Something you may not have thought about when strolling the orchards or eating your grandmother’s famous apple pie is: how did this apple come to be?

Before we get to Grandma’s apple pie, we need to rewind a little bit. Back to springtime to be specific. 

On a New England day in May, if you found yourself in an apple orchard, you would be met with sweet smells and the sight of trees covered in blossoms. If you looked more closely, you might find the secret to all the busy orchards in the fall. You guessed it, you would see lots and lots of bees. These bees are providing a critical service to the apple trees; by transferring pollen from tree to tree, they are fertilizing the soon-to-be-seeds in the apple flower. Once fertilized, the plant makes a protective and nutritious encasement around the seeds, which lucky for us, is an apple! 

A bumble bee visits an apple blossom. Image Credit: Flickr (Silver Leapers)

Apple farmers know they need pollination to occur in order to get a fruit, so many set up their orchards in a way that ensures a good fruit set. They do this by setting up what’s called “pollination partners.”  Apple blossoms only bloom for around 9 days, so it is important that there are other trees nearby that are also blooming in order for cross-pollination to occur. By planting genetically compatible trees that bloom during the same time, farmers ensure that their apple trees will get pollinated and therefore get a good fruit set. 

Honey bees (Apis mellifera) have been historically and commonly used as a way to ensure pollination in apple orchards. These days, thousands of honey bee hives are trucked in for the short, four-week apple blooming season. Some orchards also use managed bumble bees (Bombus spp.) or mason bees (Osmia spp.), although this practice is much less common. 

However, growing evidence suggests that the most important pollinators are the wild bees that are already visiting the orchards. Wild mining bees (Andrena spp.), sweat bees (Lasioglossum spp.), cellophane bees (Colletes spp.), and mason bees (Osmia spp.) are all commonly found visiting apple blossoms in spring. Not only that, but wild bees have evolved to live in harsh spring conditions, so they pollinate in colder wetter weather when honey bees refuse to forage. Even more importantly, wild bees transfer more pollen than honey bees per visit and make more visits per hour. Taken together, over the blooming period of an orchard, wild bees are much more effective pollinators than honey bees. 

To learn more about the amazing diversity and life history of wild bees you can find in eastern apple orchards, click here

Regardless of what bee visited the flowers that made your apple possible, next time you take a bite into a crispy red apple, make sure to thank a bee! And if you, like me, will be bringing in the Jewish New Year tomorrow night with the tradition of dipping apples in honey, make sure to thank many bees!

Apple dipped in apple blossom honey, what a treat! Image Credit: Sylvie Finn

*TPI tip*

You know that crabapple tree outside your house that’s just covering your yard with small rotten apples? Harvest your crabapples! Crabapples are wild apples that are edible (never poisonous!) and make great applesauce and apple butter. I made this batch from foraged crabapples I found in the area.

Homemade crabapple butter. Image Credit: Sylvie Finn