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What is Bugging You? Good Bugs vs. Bad Bugs

Flowerbeetlesept4_2 There are “bad” bugs in the garden, such as sap sucking aphids and there are “good” bugs, such as the gentle ladybugs or lacewings that patrol the perimeter of your yard. But if you are not familiar with a particular insect, how do you know if it is good or bad when you find him lurking among your flowers? And if he IS a bad guy, how do you get rid of him without completely upsetting the ecosystem of your garden?

These are the questions modern gardeners like us face everyday and sometimes there are no easy answers. But, luckily there are some great sources to help us find our way through the insect world and some safe pest control solutions.


The most comprehensive bug book I know for insect identification is called Garden Insects of North America by Whitney Cranshaw. Digthisbugbooksept4_2 It is a very user-friendly guide to common insects and mites affecting yard and garden plants. It is filled with detailed, full-color photos of every insect in different stages of life. The chapters are divided into sections such as leaf chewers, leafminers, sap suckers, trunk and branch borers, etc. If you have an insect you want to identify, you go to the section detailing the type of damage you have and then find the mug shot of your offending insect. Once identified, you go to the front of the book to determine the best mode of action. The one downfall of this book is that it focuses more on identification than on remedies. I find the remedy section lacking in some cases.


Once you are sure you have a “bad guy” infestation, you need to find a remedy that you and your garden can live with. You do not want to automatically reach for the strongest insecticide on the shelf and begin spraying indiscriminately. You will not only kill the good bugs and shift the imbalance further, but also you run the risk of impacting your health and the health of those who visit your garden or eat your produce. So, obviously you want to find a solution that does the least amount of damage to your eco balance.

There are many organic methods for pest control including integrated pest management, prevention and companion planting. But in this column, I want to cover the quick fix remedy of organic sprays. Here are four of the most popular sprays that are safe and insect specific.

Insecticidal soap is probably one of the best-known tools of organic gardeners. It is usually what you want to try first in most cases. It is a very safe pest control and yet, will knock down a wide range of insects. Just about any sucking insect is susceptible to insecticidal soap. It works very well on aphids, mites and other insects that have a hard shell. The fatty acids of the soap break down the insect’s outside covering, which causes them to become dehydrated and die. In order for the soap to work, it must come in contact with the insect. Spray the entire plant as well as under the leaves to be sure you hit them. Be careful not to hit your beneficials such as ladybugs or praying mantis as the spray will hurt them as well.
Bacillus thuringienis is a natural occurring bacterium that is known as Bt in the horticultural industry (mostly because it is hard to pronounce the name correctly). This bacteria, when sprayed on the plant foliage, will infect only soft-bodied insects such as caterpillars. It will not harm wildlife or people. Once a caterpillar ingests the bacteria, it becomes infected and dies.

I would caution you to identify the type of caterpillar you have before getting rid of it. It may be a Monarch or Swallowtail butterfly caterpillar and if it is not doing too much damage, you may want to let it complete its cycle to become a butterfly. I usually only recommend spraying when the plant’s health is in question or when you are sure the feeding frenzy is getting out of control.

Bt is the biological pesticide of choice whenever you have a caterpillar problem. Use it on tomato hornworms, tent caterpillars, corn earworms, cabbageworms, etc.

Neem Oil is horticultural oil made from a tropical tree. When it comes in contact with certain insects, it clogs up their breathing systems. On other insects, it slows their ability to eat. It does not work for all insects successfully, but has been proven to work on certain beetles such as Mexican bean beetles and squash bugs. It also works on whiteflies, leafhoppers, scales and mealy bugs.

As with all horticultural oils, you must be careful not to burn the foliage of plants you are spraying. Only spray on cool days. Spray either in the morning or evening hours to avoid leaf burn.

Spinosad is a fairly new control on the market. It is similar to Bt in that it is made from naturally occurring bacteria. However, it can be used on beetles as well as caterpillars. Spinosad attacks the nervous system of the insects and makes them immobile after they ingest foliage that has been sprayed with it. It will not affect sucking insects (such as aphids) because they do not ingest the plants. Predatory insects (lacy bugs, praying mantis) will not be affected if they are not sprayed directly. Any pests that do not eat foliage need to be hit directly with the spray. It will work on fruit flies, caterpillars, leaf miners, thrips, sawflies, and leaf beetle larvae.

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About the Author:

Theresa Loe is the founder of Living Homegrown® and the Canning Academy®. For 9 years, Theresa was the Co-Executive Producer & Canning Expert on the national PBS gardening series, Growing A Greener World®. Theresa homesteads on just 1/10th of an acre in Los Angeles with her husband, two sons and several disorderly but totally adorable chickens. Learn more about Living Homegrown here and about the Canning Academy here.