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Volume 15, Issue 8
August 2017


Watch those wasps – most are garden helpers
by Margie Lachman

Wasps! Painful stings! Why would we want them in our gardens? Surprisingly, many wasps are not aggressive and are beneficial in controlling insects that eat our plants. Of the 75,000 species of wasps, most are not aggressive and do not often sting because they are solitary and have no communal nests to defend. And female solitary wasps have ovipositors for laying eggs instead of stingers.

Nearly every harmful insect on the planet is preyed upon by wasps. They are so adept at this that the agriculture industry uses them to protect crops. Cabbage loopers, corn earworms, cutworms, even Japanese beetle larvae are used by wasps as nurseries. The beneficial wasps lay their eggs right inside the bodies of these destructive insects. After the wasp eggs htach, the larvae feed on their hosts.

Wasp eggs.

Solitary wasps are generally small and may go unnoticed except when visiting nectar plants. Take a magnifying glass into the garden and watch them enjoying a meal.

Wasps are part of nature’s natural balance. When we refrain from using broad spectrum insecticides that kill every bug, we encourage that balance. Interestingly, harmful insects multiply more rapidly than beneficial ones, which means pest populations rebound quickly and devour our vegetables and ornamentals after the poison you put out disperses. Parasitic wasps are our garden pest control partners and help to keep damage to a minimum — if they are allowed to do their job.

The two most important ways to invite these helpers into the garden are: don’t use broad spectrum insecticides that kill indiscriminately, and plant flowers that provide nectar for the adult wasps. Flowers like cosmos, zinnias, sweet alyssum, lobelia, and lemon gem marigolds are excellent choices. Many herbs like catmint, dill, parsley, and thyme are also great nectar providers.

Wasps are also pollinators, increasing the bounty from our vegetables. If we don’t disturb them they won’t bother us, but will go about their work keeping our gardens nearly free of bugs that eat our plants.

[Ed. Note: the Lemon eucalyptus oil we recommended last month has proven to be effective in keeping aggressive wasps away from picnic tables when sprayed around the perimeter of the eating area!]

Questions?  Email me at or call 503-645-2994.

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Published monthly by Pioneer Marketing & Design
Publisher/Editor:Virginia Bruce
PO Box 91061
Portland, Oregon 97291
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