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Ode to the squash bees in Oregon gardens

Photo by Jim CaneThe new squash bee found in Oregon (Peponapis pruinosa).

Wake up, the currents of bees have fled

this hour of seed

dark imaginings in their wake –

unsweet feverless drone…

No one knows what they know.

A row of empty jars fills with sunlight.

– Jennifer K. Sweeney, “Abandoning the Hives,” in “Fire and Rain: Ecopoetry of California,” 2018

Many of the poems and essays in “Fire and Rain” bear witness to landscapes, flora and fauna that were once here but are now gone, leaving it up to the ecopoets to eulogize them.

In the midst of our environmental losses, it’s uplifting to learn that Oregon has a recently arrived pollinator to celebrate: the squash bee (Peponapis pruinosa). Although “Pepo” is found throughout the North American continent, up until five years ago they had never been sighted in Oregon, making our state one of the last in the U.S. to support squash bees.

Then in 2016, a young student in “Bee Girl” Sarah Red-Laird’s Bee Biology Camp in Ashland sighted the first squash bee ever recorded in Oregon. Now the OSU Oregon Bee Atlas project is looking for gardeners to help them learn how the squash bee expands its range throughout Oregon over time.

The goal of the project is to create an inventory of all of Oregon’s bees, including the squash bee, and their plant hosts in order to monitor the bees’ health. Volunteer melittologists are trained how to look for the bees and complete a simple survey for each observation. For more information about the Oregon Bee Atlas project, or the squash bee survey in particular, visit https://extension.oregonstate.edu/bee-atlas.

Why should we care about squash bees when Oregon already has about 630 bee species? As it turns out, “Pepo” is one of the best pollinators for certain cucurbits — zucchini, winter squash, gourds and pumpkins among them — because, unlike honeybees, squash bees are uniquely equipped to digest cucurbit pollen, which is too bitter for other pollinators.

In fact, when honeybees and bumblebees do pollinate squash flowers, they do so largely by accident as they try to remove the pollen from their body. Squash bees, on the other hand, co-evolved with cucurbits so they don’t mind the bitterness of the pollen (produced by compounds called cucurbitacins). Even more importantly, the squash bees have evolved lifecycles in perfect alignment with the squashes’.

If you grow squash, you’ve probably noticed that it takes a while after the flowers begin blooming for fruit to appear. This is because squashes are monoecious plants, meaning they produce male and female flowers on the same plant. Typically, male flowers bloom a week or so before female flowers (zucchini and summer squashes are exceptions), and the flowers last for only a few hours, so there’s a very narrow window of opportunity for pollinators to transfer pollen from a male flower to a female flower.

Female squash flowers need several visits (estimates range from 8-12) from pollinators to produce well-shaped, mature fruit. Poor pollination is often the reason gardeners see immature fruit on their squash plants that fail to mature or are oddly shaped.

Squash pollination becomes even more difficult during extended periods of high temperatures like we’ve been having because they can cause plants to produce only male or only female flowers, and/or cause the flowers to wilt even faster than they do naturally.

Squash bees to the rescue! They wake up early when the squash flowers first open to begin their search for food or a mate. In fact, one way to differentiate squash bees from similar-looking honeybees is their early-morning appearance and their quick, purposeful behavior around the flowers.

Female squash bees carry pollen back to their underground nest on hairs attached to their back legs, whereas female honeybees and bumblebees are less adapted to carry the heavy, sticky squash pollen in their pollen sacs.

Male squash bees don’t bring pollen back to the nest, so females won’t allow them inside. Instead, males often sleep in squash flowers, well protected after the flower closes at the end of the day. Like all bees, male squash bees don’t have stingers, so gardeners needn’t worry about upsetting the bees if they peel open a squash flower and find one inside.

The appearance of squash bees in Oregon is important to study because they are the only known pollinator species to show up without human intervention wherever their plant hosts are cultivated. We don’t know why squash bees suddenly arrived in Oregon, but I sure am glad they did. Here’s my “Ode to the Squash Bees in Oregon Gardens”:

Welcome to Oregon,

Peponapis pruinosa!

We were so worried about

honeybees and bumblebees leaving

that we didn’t notice you had arrived.

It took the soft expectancy of a child

to spot you among zucchini and pumpkin flowers

that only have the patience

to bloom for a few hours.

Yet here you are in my garden,

exulting in bitter pollen

other bees won’t touch,

or itch off their bodies

like my dog rids his fleas.

You, alone, adore the squashes,

following them all over the Americas

for thousands of years,

changing your life to accommodate theirs,

as long-time lovers will do.

Sleep tight,

enfolded within your flower-bed.

I’ll meet you at sunrise to marvel

at your exquisite partnership

with elusive squash flowers

in my Oregon garden.

Rhonda Nowak is a Rogue Valley gardener, teacher and writer. Email her at Rnowak39@gmail.com. For more about gardening, check out her podcasts and videos at https://mailtribune.com/podcasts/the-literary-gardener.

How to attract squash bees to your garden

• Grow squash, pumpkins and gourds so flowers are available during several months of the year.

• Squash bees live in underground nests, so avoid tilling or digging heavily in the garden.

• Leave some bare patches of earth for squash bees to build nests in or near your garden.

• Provide consistent, clean water for bees to drink.

• Do not spray insecticides on your plants; they are harmful to bees.