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| The Pruinose Squash Bee (Peponapis pruinosa) pollinates large-flowered cucurbits |
The
word ‘pollinator’ conjures up images of Honey Bees for many people. But the world of pollinators is far more
complex. Our Garden Pollinators
series features some of the many interesting pollinators seen in Western Colorado
gardens. For more on pollinators in
general – and tips for attracting pollinators to your garden – see: https://mothernaturesmontrosegarden.blogspot.com/2020/06/life-friendly-gardening-planning-for.html
If
you grow any of the large-flowered Cucurbits (squash; pumpkins; gourds) you’ve
likely noticed some energetic bees who begin their day quite early. These are likely Pruinose Squash Bees, a
species with an interesting history tied the American Southwest. While now found throughout the U.S. and southern
Canada Canada – where ever squash and pumpkins are grown - Peponapis pruinosa has migrated from the native
origin of the Cucurbits, in the Southwestern U.S. and Central America. [1] For
an interesting video on the spread of this bee see reference 2, below.
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| Cucurbits like squash, pumpkins and gourds have large, open flowers |
Peponapis pruinosa is
sometimes called the Eastern Squash Bee, Hoary Squash Bee or Eastern Cucurbit
Bee; and other Bees are sometimes also referred to as ‘squash bees’. But Peponapis
pruinosa is the most important squash and pumpkin pollinator, both
in agriculture and in home gardens. [3, 4] You can see this bee anytime from
June through September, whenever the squash are in bloom. We can attest to the
pollination potential of these bees.
This year we’ve eaten, given away to neighbors and donated over 50
pounds of summer squash (so far) from just two plants!
Pruinose Squash Bees are solitary bees in the tribe
Eucerini, the long-horned bees. You likely attract other long-horned bee species
if you grow any sort of sunflower. But the Pruinose Squash Bees are specialist
bees that depend to a large extent of the pollen and nectar of cucurbits. While they mostly visit cultivated cucurbits,
they also pollinate wild cucurbits such as the Cucurbita foetidissima (commonly
known as the buffalo gourd, calabazilla, chilicote, coyote gourd, fetid gourd,
fetid wild pumpkin, Missouri gourd, prairie gourd and stinking gourd). [4]
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| Pruinose Squash Bee (Peponapis pruinosa): common view |
The
Pruinose Squash Bee is slightly smaller than the European Honey Bee and the
females have hairy legs (Honey bees have smooth legs). See reference 5, below
to learn how to tell Squash Bees from Honey Bees.
The
thorax is usually orange, the abdomen is black with whitish bands and it’s covered
in yellowish hairs.[4] Branched hairs (scopae)
on the females hind legs help to carry the large, coarse pollen of cucurbits. This pollen is the sole food eaten by
offspring while in the nest. For some
good pictures of Peponapis pruinosa see references 4, 6 and 7, below.
The
entire life of the Pruinose Squash Bee is tied to
the squash plant and its large flowers. Females build their nests in the ground
near squash plants. The nests can reach 1 ½ ft. deep. Females produce one new generation a year.
They lay their fertilized eggs in cells in the nest and provide stored squash
pollen provisions for the larvae to eat. The offspring over-winter as larvae in
the nest, emerging as adult males and
females in early summer. [8]
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| Pruinose Squash Bee (Peponapis pruinosa): well adapted for pollinating cucurbits distinctive floral anatomy |
Females
gather pollen in the morning, when squash flowers are open. In fact, squash
bees can actually begin pollinating when it’s still quite dark – likely one
reason why they are such good pollinators. Squash bees can actually see in the
dark! [8] And squash bees are very
active, since they must complete their work before the flowers close mid-day. Males forage for food and mate with females in
the open flowers. The males sleep in the closed flowers in the afternoon, often
several males per flower. Females work in their nests in the afternoons.
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| Pruinose Squash Bee (Peponapis pruinosa): in summer squash blossom |
Peponapis
pruinosa faces
several threats in the agricultural setting.
Any activity that disturbs the soil, such as plowing, harrowing or discing
may destroy the underground nests. In
addition, commonly used agricultural chemicals can pose a risk to any
ground-nesting bee species. [9] In the home garden, limiting both ground
disturbance and the use of pesticides are good ways to safeguard the
ground-nesting bees.
Why
enjoy the Pruinose Squash Bee in your garden? Well, they’re interesting to
observe, particularly if you’re a morning person. And if you want a good crop
of Cucubits, this docile pollinator is truly your best friend. So, welcome this Southwestern native bee into
your garden with an open heart. You’ll
be well-rewarded!
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2. The
Squash Bee (Peponapis pruinosa) - Bee Mission
4. Peponapis pruinosa - Wikipedia
5. (221) Squash Bee
Identification: squash bees and honey bees - YouTube
6. Species Peponapis pruinosa -
Pruinose Squash Bee - BugGuide.Net
7. Squash
Bee, Peponapis pruinosa (uci.edu)
8. Squash Bees
(sharpeatmanguides.com)
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We welcome your comments (below). You can also send your questions to: monaturesmontrosegarden@gmail.com
