by Susan Mulvihill
As an organic gardener, I am very careful to only use
environmentally-safe products for the occasional insect problem.
For example, I’m
a huge fan of using floating row cover when growing veggie crops that typically
have insect issues, such as cabbage family crops, spinach, beets and Swiss
chard. And there's nothing wrong with that.
But I have also occasionally used organic sprays such as Bt (Bacillus thuringiensis) to control cabbage
loopers and tomato hornworms, or Safer’s insecticial soap when dealing with
aphids. Here I thought I was being such a good steward of the
environment around me but it turns out that’s not necessarily so.
After reading Jessica Walliser’s book, “Attracting
Beneficial Bugs to Your Garden” (Timber Press 240 pp., $24.95), I now know that
even organic sprays can cause problems. For one thing, they can be more harmful
to beneficial insects than to the pest insects I’m targeting. Yikes!
And if you knock off the good guys, other types of pest
insects can become more prevalent in the garden. Suddenly the balance in your
garden’s insect world is completely off.
An interesting fact I read in Walliser’s book is that only 1
percent of insects are damaging types, and the other 99 percent are either
beneficial insects or ones that do no harm. As gardeners, doesn’t it always
seem like there are way more pest insects than that?
As the author puts it, “All these tiny (beneficial) insects
are a vital part of your garden. Their inherent intent, of course, is not to
help you control pests but rather to survive and reproduce. Isn’t it nice,
however, that your garden reaps the benefits of their consumptive and
reproductive needs?.... Learning to recognize these natural enemies and
encouraging ample populations of them results in a clear win-win situation for
both the insect and the gardener.”
Aha, so that really should be our goal, don’t you think?
First of all, she underscores the need for us to have a
pesticide-free environment. For one thing, this will eliminate the resistance
to chemicals that pest insects have a tendency to develop.
Second, we need to add plants that will shelter and support
Walliser points out that, in order to survive and reproduce,
beneficial insects need proteins found in pollen and carbohydrates found in
nectar. She says it’s best to have both pollen and nectar sources in one place
in our gardens so the beneficials don’t expend energy trying to find each.
Within this book, the author has useful photos for
identifying beneficial insects and information that indicates which types of
insects they prey upon. Next are detailed profiles of plants that attract and
nurture beneficial insects. I’ve known for years that members of the carrot
family (Apiaceae) attract them, but her information goes way beyond that.
Then there is a guide to landscaping for beneficial insects
so it is seamlessly incorporated into our gardens. She refers to these areas as
insectary borders, “areas intentionally created to support the nutritional and
environmental needs of insect predators and parasitoids.”
And finally, she puts all of the information together in a
simple guide that shows each beneficial insect, the insects they eat and which
host plants will keep them in your garden.
Walliser has a very enjoyable writing style. She’s quite
self-effacing, admitting prior ignorance about the world of insects and
admitting she used to spray a lot of pesticides. She also shares that she used
to hate bugs because they damaged what would otherwise be “perfect” plants in the
In my humble opinion, this book should be required reading
for all gardeners! It contains excellent information on insects and
their habits, and encourages gardeners to select a diverse collection of plant
species for the most success at drawing in beneficial insects.