Attention, spheksophobes: Wasps just want
to help.
And Heather Holm wants to help them make their case
to gardeners and others.
Holm, a
biologist and pollinator conservationist,
knows it’s not an easy sell. But in her recent book, “
Wasps: Their Biology,
Diversity, and Role as Beneficial Insects and Pollinators of Native Plants,”
she asks that we consider wasps — and not just their cousins, the bees — in the
plant choices we make and the pollinator-friendly gardens we create.
اضافة اعلان
“If we took wasps out of the equation,” she said,
“many of the leaf- and seed-eating insects they prey on would just go
unchecked.”
Troubled by cabbage loopers chewing on your
brassicas? There’s a wasp for that.
There are also wasps that target tarnished plant
bugs (a pest with a taste for a wide range of vegetables and small fruits) and
ones that prey on brown marmorated stink bugs and fall webworms. All such
sustenance is brought back by adult female wasps to provision their nests, as
food for their larvae.
The list of the organic pest control services
offered by wasps goes on, and yet it is the wasps that we humans reflexively
regard as pests. That reputation is the result of just 1.5 percent of the total
wasp species in
North America — the ones that build social nests above or below
ground, forming colonies and cooperatively living in multigenerational nests
during the breeding season to rear the next generation.
The irony: It is the social wasps toward whom we
feel anti-social. They have inadvertently tainted our view of the other 98.5
percent (although, to be fair, the social ones provide ecosystem services,
too).
The trigger is typically a run-in with ground-nesting
yellowjackets (Vespula). Or a too-close encounter with a nest of paper wasps
(Polistes) or perhaps with a larger, more complex nest of bald-faced hornets
(Dolichovespula maculata), its many layers of combs enclosed in an envelope.
The result is a sting — always delivered by a female — that we just cannot
forget.
If the wasps had been nectaring on flowers they
would have paid us no mind, Holm is quick to point out. But when we threaten
their nests — the home to the next generation — their best defense is a good,
and painful, offense.
“The flower garden is the restaurant, not their home
— they don’t defend it,” Holm said. “But social wasps are very inclined to
defend their home.”
Flowers a wasp could love
Wasps need habitats similar to those preferred by
bees. But bees eat a plant-based diet. Their prey-seeking cousins, the wasps,
need something more: to be around the specific plants that attract the insects
they hunt to feed their young.
Wasps make up 15 percent of the total number of
flower-visiting insects worldwide. But they are regarded as incidental or
secondary pollinators, not the pollination machines that bees are designed to
be, with their hairy bodies that pollen granules cling to.
Another anatomical difference: The range of
flowers that adult wasps can drink nectar from is limited because their tongues are
typically shorter than those of bees. While choosing native plants is important
when you’re creating a habitat that supports beneficial insects, the wasps have
an additional request: simple, shallow flowers, please.
Oh, and lots of wasps love the color white, as many
of those examples underscore.
Remember the restaurant-versus-home analogy, she
said, and go ahead: Start planting with wasps in mind. Enhancing the
garden with their preferred flowers will not increase your chances of being stung —
and it might make your vegetable garden a more resilient place.
Limiting the risk of getting stung
But what’s the best way to discourage them from
stinging — and to avert the near-inevitable human impulse to spray some
chemical from a distance to eradicate an established nest, killing all of the
individuals in it?
Intervene early, Holm advised, to dissuade
nest-building in high-risk spots, sparing risk to yourself and to whole
colonies, above or underground. “Don’t even think of trying to intervene in
August,” she said.
One insight toward that end: Yellowjacket females,
probably the wasp most often responsible for stinging humans, search out
preexisting cavities, like rodent holes in the ground, when they are emerging
from winter hibernation in early spring. Try closing up those holes
proactively.
And if you had a ground-nesting colony in the yard
last year, look there first, Holm recommended, because wasps will often search
for and initiate a nest near the site of their natal one.
Similarly, check eaves, overhangs, and birdhouses early and
regularly for any sign of the construction of a nest comb, she said, “when
maybe there is only an occupant or two involved.”
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