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Managing Insect Pests Without Using Dangerous Chemicals

We all have a wide variety of insects in our gardens and landscape.  Most of them, 95%, are beneficial and we could not live without them.  The other 5% are what we call pests.  Some are a nuisance and others can be dangerous.  This is especially true for individuals who are sensitive or allergic.  Even beneficial insects such as ants, honey bees or pill bugs can be a problem when they invade our homes.

Sometimes, we are our own worst enemy.  To landscape our property we plant woody ornamentals like althea or crepemyrtle.  These attract mealy bugs and aphids.  These pests suck sap out of the ornamental trees and produce a sugary substance called honeydue.  This is a favorite food of many ant species.  We attract the ants to our home and then wonder why we have ants on the kitchen counter.

Many people simply don't like bugs.  At the first sign of any insect they run out to the garden center or home improvement store to purchase an insecticide.  Many of these products contain harsh chemicals that can endanger the health of our family and pets, even when used according to label instructions.

So what can we do?  Long before the use of pesticides, farmers and gardeners knew that certain plants grew better when planted next to other plants.  Herbs grown next to vegetables can improve the flavor and the growth of our crop plant.  Plants can also return minerals and nutrients to the soil.  Flowering plants will attract birds and beneficial insects that prey on those insects we call pest and plants can repel harmful insects.  The relationship between plants and insects is known as "companion planting".

Herbs and flowering plants repel insect pests through their odors or root secretions.  Repellent plants generally have a strong scent.   Insects rely on their antennae to sense or "smell" the plant they prefer to eat or lay eggs on.  The companion plants mask the scent the pest is looking for and the oils can be an irritant.  The exact mechanism by which many companon plants protect our garden is not known.  In fact, there are skeptics that say this is nothing more than folk lore.  From personal experience, I know companion planting works.

Organic means of control are not always 100% effective.  That can be said of the harshest, most toxic chemicals as well.  We are not attempting or expecting to totally eliminate pests from our gardens.  Our goal is to promote a healthy, vigorous garden yielding beauty and a bountiful harvest.

The following is a guide to help you experiment and determine which companon plants work in your garden.

Artemisia - Also known as Worm Wood, deters slugs.

Bachelor's Buttons - Attractive to beneficial insects including: ladybugs, lacewings and beneficial wasps.

Basil -  Repels flies and mosquitoes and improves the flavor of tomatoes.

Bee Balm - Plant with tomatoes to improve growth and flavor.

Catnip - Repels flea beetles, aphids, Japanese beetles, squash bugs, ants and weevils.  A component of the essential oil in the Catnip plant (Nepeta cateria) repels mosquitoes 10 times more effectively thean DEET.

Chives - Improves growth and flavor of carrots.  Repels aphids and spider mites.

Garlic - Discourages aphids, spider mites, flea beetles and Japanese beetles.

Lavender - Deters moths, aphids and fleas.  Some say dried lavender will repel scorpions.

Marigold - Deters Mexican bean beetles, squash bugs, thrips, tomato hornworms and whiteflies.  The roots will repel harmful root knot nematodes that will destroy tomatoes, potatoes, roses and strawberries.  At the end of the growing season turn the marigolds under so the roots will decay in the soil.

Nasturtium - Helps control squash bugs, cucumber beetles and whiteflies. 

Onions - Repel carrot flies.

Parsley - May be used as a "tea" to repel asparagus beetles.  Parsley gone to seed will attract parasitic wasps which are beneficial.

Pennyroyal - Deters fleas, mosquitoes, ticks, gnats, flies and chiggers: rub the leaves on your skin.

Peppermint - Deters white cabbage moths, aphids, flea beetles and squash bugs.  Will also repel mice.

Rosemary - Repels cabbage moths, bean beetles and carrot flies.  Prostrate Rosemary deters snails and slugs.

Sage - Deters cabbage moths, beetles and carrot flies.

Tansy - Deters Japanese beetles, striped cucumber beetles, squash bugs and ants.

Thyme - Repels cabbage worms, carrot flies and attracts beneficial insects.

Yarrow - Attracts beneficial insects.

These herbs and flowering plants will repel unwanted insects, attract beneficial insects, add beauty to our world and are wonderful to cook with.  Some are annuals and must be replanted each year.  Most are perennial and will return year after year.  Soon you will enjoy sharing cuttings and seedlings of these herbs with your friends.

Unfortunately, most of us are impatient.  We want results right now.  It is so tempting to reach for that can of insecticide.  Resist!  Initially, while your companion plants are maturing, you can control pests with botanical oils, insecticidal soap, horticultural oils and by releasing beneficial insects and nematodes into your yard or garden.

Restoring the natural order in our own personal environment will take time.  Take your focus off the destination and enjoy the journey.


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