Gardening Sweet Spots
By Donna Hessel
How to Tell the Difference
My friend wrote, “A couple years ago, I noticed my dahlia stems were lined with black aphids. I planned to spray them with water from the hose the next day, but noticed a large, black beetle, a ladybug and a daddy long legs eating the aphids. I left them alone and in two days all the insects were gone.”
This is an ideal scenario and the goal of garden pest management! In this blog, we’ll identify some of the good and bad bugs that are in gardens in our region, learn how to identify which is which, and give suggestions on how to achieve the good bug/bad bug balance a garden needs.
What is Integrated Pest Management (IPM)?
If aphids, tomato hornworms, mealybugs and other “bad bugs” are attacking your plants, you need some beneficial insects to control them. Beneficial insects are a part of Integrated Pest Management (IPM). They are the first step in a strategy that also includes biological, cultural and chemical methods to control garden insect pests. Insect pests have evolved as part of a food chain. The IPM method uses this system to encourage pests’ predators to control infestations. Beyond biological controls, IPM recommends cultural controls such as crop rotation, proper plant spacing, pruning and maintaining appropriate watering and fertilizing. Traps, barriers, hand-picking pests and mulching soil are suggested mechanical and physical controls. Low-toxicity and environmentally friendly chemicals with targeted application are used only when necessary.
Some of the Good Bugs
Lady Beetles (or Lady Bugs) – You are likely familiar with this insect – Lady bugs have a dome-shaped body, wing covers with red or orange spots. Their Latin name is Coleoptera, in the family Coccinellidae (Latin for scarlet). Lady bugs gobble up aphids galore, but they also eat scale, mites, small insects and/or their eggs. They also feed on pollen and nectar. If lady bugs don’t inhabit your garden, order some online (but you will need the bugs they eat in your garden, too, in order to keep them in your garden).
Cotesia wasps are parasitoids that eat caterpillars. (Parasitoids are insects whose larvae live as parasites that eventually kill their hosts — typically an insect.) These wasps are small, black insects with long antennae and four wings.
You can find them on tomato or tobacco hornworms, which they use as a host to deposit their eggs. The wasp larvae eat the caterpillar inside out, emerging as long white cocoons extending from the caterpillars.
Hover flies, in the family Syrphidae, have yellow-and-black bee-like markings. You can tell them apart from bees because they have only two wings, not the four found on bees and wasps. Their antennae are short and their eyes appear to wrap around their heads. Hover fly eggs produce maggots, which eat aphids.
Only the larvae feed on other insects. Adult hover flies need nectar and pollen, so pollinator plants, such as hyssop, should also be included in the garden. While aphids are their main prey, they also feed on thrips and small caterpillars. There can be seven or eight generations per year.
Green Lacewings – In the larval stage, these good bugs are ravenous predators of aphids and other soft-bodied insects such as mealybugs, caterpillars, thrips, leaf hoppers and other sap-sucking pests. Their Latin name is Chrysoperla carnea. Adults eat pests on peppers and the larvae of Colorado potato beetle, which you may see on both potatoes and eggplants. Green Lacewings need nectar- and pollen-producing plants in order to stay in your garden. They love aphid-produced honeydew, a sugar-rich sticky liquid, which seeps from damaged plants onto leaves when aphids are active.
Ground Beetles/ Bombardier Beetles – These are good bugs that help eliminate other pests. Some of their prey includes larvae and adult caterpillars, cutworms, march flies, slugs, thrips, snails, aphids, ants, termites and grasshopper eggs.
Bad Bugs to Watch Out For and Controls
Roseslug Sawfly Larva Leaf Damage
Roseslug Sawfly (Endelomyia aethiops) – These half-inch-long yellow-green caterpillars with an orange head are active from spring to early summer. They look like flies but are actually wasps. They eat all kinds of roses. They chew and scrape the upper surface of leaves creating a windowpane effect. The damage is mostly cosmetic. To control them using IPM, you can handpick caterpillars early in the season or spray them with a strong stream of water. You can spray upper and lower leaf surfaces early in the day (for cooler temps) with insecticidal soap. Beetles, birds and parasitic wasps feed on these bugs.
Two-Spotted Spider Mite (Tetranychus urticae) – These will be hard to spot as they are 1/50th of an inch long! They range in color from rusty green to brown, yellow, red or orange with two spots on their backs. They produce multiple generations per year and are active all summer. They eat more than 200 plant species!
With piercing mouthparts they feed on the undersides of leaves, causing a stippled or mottled appearance. They also produce webbing. Prevention is the best control. Mulch around plants, choose drought-tolerant plants and don’t fertilize during a drought. Spraying with water can dislodge them from plants.
Spotted Lanternfly (Lycorma delicatula) – There has been a lot of publicity about these insects in our region. The one-inch-long insects have brown forewings with black spots and black, white and scarlet wings. They are active spring through fall and produce one generation per year. They eat more than 100 plant species, including grape vines, hops, maple and fruit trees and ornamental garden plants. Damage from their piercing mouthparts includes oozing sap, wilting, leaf curling and dieback. They also produce honeydew. IPM controls include removing Alianthus trees (tree of heaven) as it is a favorite host plant. If you see the distinctive 1-inch-long egg masses that look like smeared mud on tree trunks, remove them.
Lantern fly egg mass
Four-lined plant bug (Poecilocapsus lineatus) – This bug is 1/3-inch long, is green-yellow, and has four black stripes. It is active late spring to early summer.
It feasts on more than 250 plants but is especially fond of plants in the mint family. Plant damage looks like black or brown spots, often suspected to be fungal disease.
IPM management includes insecticidal soap to get rid of nymphs. Hold a container of soapy water under the foliage and tap the plant so the insects fall into the water and drown.
Two or three-inch scarring on stems indicates where adults have laid eggs. Remove these leaves and destroy them to eliminate the next generation. Larger adults can be handpicked.
Bagworm (Thyridopteryx ephemeraeformis) – You’ve probably seen the “bags” that contain the gray caterpillars with dark spots that are inside the bags. The bags start small but grow larger as the caterpillars grow and add more foliage.
Bagworms have one generation per year. They are active spring through summer. The bags can be found on a wide range of conifers. Bagworms also feed on deciduous trees. They eat the needles and foliage of their host tree. As they grow, they can cause serious defoliation.
Pull the bags or cut them off while they are small and trash them. For larger trees or infestations, spray Bt (a natural, soil-dwelling bacterium used as a biological pesticide for specific insects) when young bagworms emerge in late spring to early summer.
Mealybugs – These usually appear as colonies of white fluff that turn into cottony masses on plant leaves and stems (on both outdoor and indoor plants). They suck plant saps, weakening the tissue. Plants become spotted, discolored, stunted and distorted. They can be controlled by isolating infected plants and wiping the bugs off with a soft, wet sponge or other soft material dipped in alcohol. Use insecticidal soap mixed with water to spray outdoor plants.
Stink Bugs, so called because they have a nasty odor if crushed, are about half inch long and wide. They are generally dark brown with a creamy tannish underside. They eat tomatoes, corn, beans and other garden vegetables. Apples, peaches and pears are favorite fruits, as well as shade trees and roses. Destroy egg masses on the underside of leaves starting in June. There are multiple generations in a season. Providing plants that attract their natural enemies, such as lacewings and ladybugs, will help to control them. Neem oil can be used. Occasionally, in the fall, you may find one in your house that is looking for a cozy winter hideout. Be careful not to crush it when you catch it to destroy. Larger indoor infestations can be swept up with a vacuum cleaner.
How to Tell the Difference Between Good and Bad Bugs
Look at the insect to see what it is doing to your plant. Take a photo of it. If it is eating your plant, it is probably a bad bug. Is there one or more? If there are a lot, infestation may be the problem. Compare your photo to photos of previous bugs you may have destroyed. Check a bug identification website, such as insectimages.org, to find a comparable photo. A common way to identify a bad bug: Slow moving insects are generally bad while fast moving ones are generally good…generally.
Other Controls
- Birds and Bats These creatures eat an enormous quantity of bugs – good and bad.
- Spiders, Centipedes, Dragonflies, Frogs, Toads and Lizards If you have a pond, you will have frogs. Frogs eat moths, flies, grasshoppers and cockroaches. Lizards eat a wide variety of insects. Toads in your garden will help to manage insect invasions. While spiders are not insects (eight legs vs. six), they are extremely helpful predators in the garden and consume many types of insects.
- Companion Plants Planting specific flowers will help to control specific bad bugs and attract specific good bugs. Some combinations are dandelion, anise and celery for wasps; marigold, chamomile, hyssop for hoverflies, wasps; clover for ground beetle; ivy for wasps, houseflies; stinging nettle for many good bugs; sunflower for lacewings, wasps; ragweed for strawberry leaf bugs; strawberry for oriental fruit moth larvae; yarrow for ladybugs, wasps; tansy, sweet fennel, angelica, cosmos, dill, goldenrod for ladybugs; mustard for a wide range of parasites; amaranth for ground and bombardier beetles.
The goal is not to completely eradicate bad bugs or overpopulate your garden with good bugs. The goal is to achieve a balance, and a balance is what a garden needs to thrive. Look closely at your garden and try to identify both the good and bad bugs you find.
Article References
IPM Insect Management article https://www.bing.com/search?q=ipm+methods+for+pest+control&FORM=QSRE9
Good Bug Bad Bug: How can you tell the difference? By Tom Oder
https://www.treehugger.com/good-bug-bad-bug-how-can-you-tell-the-difference-4864052
Good vs. Bad Garden Bugs: How to Know the Difference – April 22, 2026 – by Tony O’Neill
https://simplifygardening.com/good-vs-bad-garden-bugs/
The Root of It – “Beneficial Insects” – July newsletter – Summit County MG by S. Vradenburg
Garden Gate “Notes” – Online Newsletter 6-11-26, “Garden Pests to Look Out for in the Midwest” and “Garden Pests to Look Out for in the Northeast” by Sherri Ribbey
Photos from Google Images and Bigstock
