Good bug or bad bug? How can you tell? A few tips and pointers to help you identify insects in the garden.
Good Bugs or Bad Bags in the Garden
Cue the scary music…the theme from Jaws….
Today’s blog post will deal with the bad bugs. The bad guys. You know who. The ones who devour your plants, who ruin your crops, and who make your family question the time, money and effort you’ve spent on your gardening hobby.
What Is a Bad Bug?
‘Bad bugs, bad bugs…whatcha gonna do when they come for you?’
Sorry, I couldn’t help but sing the theme from Cops. In all seriousness, why do we call some bugs “bad” and some “good?”
The distinction is similar to the one I heard an old gardener say when asked what the difference is between a weed and a flower. “A weed,” he said upon careful reflection, “is just a flower you don’t want growing in your garden.”
Bad bugs, then, are insects we simply don’t want in our garden because they are pests. They cause problems with the healthy, fertility or productivity of our fruit and vegetable gardens, or the ruin carefully cultivated flowers and plants.
The Top 3 Bad Bugs
It was hard to select my top three ‘bad bugs of the garden’, but the following seem to be the ones I battle most frequently here in my Virginia garden. Your particular nemesis may be different than my own. It’s important to learn to recognize the problem insects in your particular gardening zone. Taking a class at your local Cooperative Extension office, or even visiting their website and taking advantage of the numerous free resources they provide, is a great start.
Bad Bug #1: The Japanese Beetle
The Japanese beetle seems to be the scourge of every garden. Starting in mid June around Father’s Day, a swarm of these iridescent insects descends on my garden. They quickly consume the apple tree leaves, then move on to my cherry trees. They devour the ornamental plants and make the green bean leaves look like lace.
The USDA offers a free downloadable book on Managing Japanese Beetles that shares useful information on controlling these insects. They lack natural predators in the United States, which accounts for their strong numbers in the garden.
One of the keys to managing Japanese beetles is to manage them during each portion of their life cycle. As grubs, they burrow through the lawn, eating roots and causing brown patches. Treating the lawn for grubs disrupts the life cycle and leaves fewer beetles to harm garden plants.
Bad Bug #2: The Tomato Hornworm
I never saw a tomato hornworm until I moved to Virginia. Then I saw them on every tomato plant. These ugly worms are also called tobacco worms, and my area of the state was once a huge producer of tobacco. I can only imagine that this created a sort of nursery for the tomato hornworm that kept their numbers strong to this day.
Tomato hornworms are difficult to see in the garden because they blend in so well with the stems and leaves of the tomato plant. You are more likely to view their damage in the morning after a night spent feasting on your tomato plants. They can strip a young plant bare of leaves in a single night.
The best method that I know of to control for the tomato hornworm is to plant marigolds, especially the old-fashioned ones that have a strong scent. Tomato hornworms really do hate the smell and avoid the area. You can also pick them off by hand, but be warned; they are nasty when squashed. Trust me on that one.
If you see a tomato hornworm with white rice-like bits sticking out of it, leave it alone. Those tiny grains of rice are actually the young of a particular species of wasp that lays its eggs on the hornworm. The young eat the hormworm alive. Eventually, it dies and the baby wasps continue their journey. Nasty bit of nature’s control over the hornworm, but it does work – and it will limit their ability to harm your plants and certainly kill the hornworm. Leave it alone.
Here is more information from the Colorado Cooperative Extension on the tomato hornworm.
Bad Bug #3: Colorado Potato Beetle
Unlike the Japanese beetle, the Colorado potato beetle isn’t an import into the United States. Rather, it was found almost exclusively in the West and Midwestern portion of the United States. Early settlers in the area planted potatoes, and the beetles found the leaves of the potato plant more to their liking than the native buffalo bur plants which they had traditionally consumed. As they are more, they grew more prosperous and began spreading eastward. Today, they’re a major pest on most potato crops. They will also eat eggplant and tomatoes if they can’t find potatoes.
Adults appear on the leaves of plants. Adult beetles are fairly small and have a telltale striping along the back. They mate and lay eggs on the underside of the potato leaves. The orange-red larvae chomp on the leaves, finally growing into adults who continue the cycle.
Commercial insecticides are mostly useless against the Colorado potato beetle. I can vouch for that. There are two times when I’ve reached for the commercial insecticide, Sevin, in my garden. Once was to control squash beetles and the other, Colorado potato beetles. Both time it didn’t work as well as I had hoped.
The best method I’ve found to control the Colorado potato beetle is hand picking. It’s disgusting, but it works. Take an empty glass jar, such as a jar from spaghetti sauce. Clean it, then squirt about a tablespoon of dishwashing liquid into the bottom of the jar. Fill the jar 1/3 of the way with water. Wear gloves, and as you walk through the garden, flick the beetles into the soapy water with your fingers. They can’t swim out and the soap makes them too slippery to escape, so they drown. Discard the beetles and water at the edge of the garden (I throw mine into the woods) or screw the lid onto the jar and throw the whole thing away.
An organic control said to work well is Bacillus thuringiensis var. tenebrionis. BT is short for Bacillus thuringiensis, a very popular biological control for many insects and diseases. It acts upon the larvae and kills them. I have no tried it yet, but I hope to if I grow potatoes again. This year’s crop was almost entirely destroyed by the Colorado potato beetle, a dreadful garden pest if I’ve ever seen one.
Are there more garden pests? Unfortunately, yes. White flies, aphids, the aforementioned squash beetles and more. But these are the top three scourges in my Virginia vegetable garden.
When Good Bugs Go Bad
This is a true story…good bugs can sometimes be bad bugs, especially inside the home.
About a month after we moved into our new home in Virginia from New York state, I had to return to New York for a business meeting. Just before I left, a lady bug invasion entered our home. We had lady bugs everywhere – coating the ceiling, clustered behind the pictures on the walls, you name it. It got so bad that I wore a big floppy straw hat while working in my office because the lady bugs would fly straight into my head, get tangled in my hair, and in their panic, bite. Some people say, “Lady bugs don’t bite!” and I suppose that is technically true since they do not have teeth. Whatever they have, they pinch with it when they are frightened, and it hurts like heck.
Anyway, these so-called good bugs turned into bad guys inside the house. Not only did they become a nuisance, they made a mess. And vacuuming them up made the vacuum cleaner stink after a week or two. It got ugly, fast.
After I arrived at my sister’s house in New York, I called my husband that evening to let him know I’d arrived safely in New York. He sounded upset.
“I can’t get the heat to turn off,” he said.
It was over 80 degrees inside the house, and the heat just kept blasting from the radiators. We walked through all that we knew about the system; remember, we were just getting used to it. Finally, in desperation, he called the repairman.
When the repairman opened up the heating unit outside, what did he find? A lady bug, crisped to a cinder. It had crawled inside one of the electronic chips and shorted it out. The short caused the system to turn on, but it could not turn off.
Needless to say, I do not find lady bugs cute anymore.
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Jeanne Grunert is a certified Virginia Master Gardener and the author of several gardening books. Her garden articles, photographs, and interviews have been featured in The Herb Companion, Virginia Gardener, and Cultivate, the magazine of the National Farm Bureau. She is the founder of The Christian Herbalists group and a popular local lecturer on culinary herbs and herbs for health, raised bed gardening, and horticulture therapy.