Southern Roots

Plant those Pests

By Verna Gates  |  Photography courtesy Mark Peavy

A wide variety of plants have natural defensive actions against bugs and planting these repellants in the garden can aid you too.

As I was purchasing a can of Skoal dipping tobacco at my neighborhood convenience store, the confused neighbor standing behind me asked, “Picking up some bad habits, are we?”

“I’m not, but my roses are,” I replied. We proceeded to hold up the line for the next 10 minutes, along with other interested parties joining in, discussing aphids and homemade insecticides. The store sold out of Skoal, so they didn’t mind.

Tobacco, like so many plants, are natural bug repellants, and bug killers. In the centuries before man began growing and harvesting, plants were being chomped on by insects. The plants launched defensive actions against these savage attacks by developing toxins, like nicotine, in their leaves and stems. That is why tomato leaves emit such an unpleasant aroma, designed to discourage bugs, which certainly hasn’t slowed down human consumption for the tasty fruit.

Some of the smarter plants evolved defenses that even smarter humans have taken advantage of for centuries. Long before chemists produced insecticides, humans borrowed defenses against pesky bugs from marigolds, rosemary, and lavender.

Marigolds welcomed visitors at the doors of old homesteads with their bright flowers.  While they are pleasant plants for human guests, these plants roll out the unwelcome mat for fleas, ticks and mosquitoes.

“Marigolds are the real deal when it comes to insects,” said Blake Layton, Mississippi State University Extension. Layton is an entomologist and avid gardener. “Plant them next to tomatoes, and nematodes won’t grow and impact your tomatoes.”

As the bane of any summer night, mosquitoes can make backyard barbecues miserable with itchy bites. Citronella, or lemongrass, is a major ingredient in many repellants, such as candles. You can get a swat up on mosquitoes by growing it either in clumps around the patio, or in pots that can be moved from the grill to the picnic table. Its strong scent blocks the human smell that attracts bugs to our blood.

Chrysanthemums produce an ingredient often found in insecticides, pyrethrums, which can be found in indoor sprays, pet shampoo, and bug bombs. It can kill everything from bedbugs, roaches, ants, Japanese beetles, ticks, silverfish, lice, and fleas to root-knot nematodes.  

My grandmother kept a sachet of fresh lavender in her drawers to keep out moths. A plot or pots of lavender will discourage mosquitoes, gnats, fleas and flies. You can even use lavender oil as a repellant on your skin. An added benefit, unlike stinky marigolds and citronella, lavender will aid sleep in two ways — no itchy bites and a pleasant, soothing fragrance.

It used to be so effective, it was burned in hospital rooms through the time of Napoleon as a sanitizing agent and to rid the place of pests. Scent is in the nose of the sniffer. While humans love the scent of rosemary, bugs do not. Rosemary can be planted as a companion plant to discourage vegetable garden pests, or closer to home to ward away mosquitoes. Burn it in the charcoal or fire pit to spread its oils. Make your own homemade repellent by boiling a quart of rosemary in a quart of water. Strain. Store it in the refrigerator for a refreshing bug spray! When the scent fades, it loses effectiveness.

Insects rely on scents to find their prey and few things put out a stronger scent than the onion family. Plant any of the alliums in your garden for a broad-spectrum pesticide. Critters such as slugs, carrot flies, cabbage worms, and aphids dislike onions and your tomatoes, peppers, eggplants, potatoes, broccoli, cabbage, and carrots will thank you. So will your roses. Whether you are growing chives, leeks, shallots, or onions, you can also spice up your vegetable pot with their flavor.

For personal protection, many of the herbs provide relief from the bugs that see you as a personal snack. Basil, lemon thyme, lemon balm, mint, and bay leaves can be planted to distract the flying pests. Catnip uses a chemical called nepetalactone to attract flies and felines; it can also draw away mosquitoes, deer ticks, and roaches.

For vegetable gardeners, a number of plants repel specific attackers. Petunias are sometimes referred to as “nature’s pesticide.” This powerful plant can ward off tomato hornworms (which are big, ugly plant killers), asparagus beetles, leafhoppers, and squash bugs. As an added benefit, they are easy to grow and can be planted in your vegetable beds.

Other plants help out in the vegetable garden, such as thyme (whiteflies, cabbage loopers, cabbage maggots, corn earworms, whiteflies, tomato hornworms), parsley (asparagus beetles), and dill (squash bugs, spider mites, cabbage loopers, and tomato hornworms).

If these plants fail you, Layton recommends a good dose of Permethrin, which is a chemical insecticide based on the killing properties of the Permethrin daisy, a native to Australia and South Africa.

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