Insects
Good Bug, Bad Bug, Benign Bug
A quick guide to common good bugs, bad bugs, benign bugs, and Integrated Pest Management (IPM) for home vegetable gardens.
Good Bugs
Good bugs are beneficial insects and arachnids in the garden. They are often predators that feed on bad bugs in vegetable gardens. Common good bugs include lady beetles, lacewings, assassin bugs, spiders, predatory stink bugs, parasitic wasps, earwigs, big-eyed bugs, minute pirate bugs, dragonflies, syrphid flies, hover flies, and praying mantid.
Pollinators pollinate many crops, which is the most common way crops that rely on cross-pollination produce fruit.
Common pollinators include bees, butterflies, moths, flies, and beetles.
Common crops that rely heavily on pollinators generally include crops that produce fruit, such as apples, tangerines, lemons, almonds, blueberries, cucumbers, onions, summer squash, pumpkins, watermelon, and blackberries.
Bad Bugs
Bad bugs are insect pests that eat plant leaves, stems, and fruit and can wreak havoc on plant health and appearance. Common bad bugs in vegetable gardens include aphids, mealybugs, whiteflies, thrips, spider mites, leaf-miners, stink bugs, leaf-footed bugs, hornworms, armyworms, cabbage loopers, southern armyworms, tomato fruitworms, tomato pinworms, yellowstriped armyworms, snails, and slugs. Snails and slugs are not insects yet they are often considered garden pests.
Benign Bugs
The vast majority of insects have neither a positive or negative influence in our lives and gardens. Insects are the foundation for our ecosystem and it is important not to overreact to insects in our gardens. Needlessly using pesticides on insects that will not harm your garden can be harsh on your wallet and the environment.
Armyworms can defoliate an entire crop if not managed. They metamorphize into moths.
Good Bug or Bad Bug?
There are lots of lookalike species out there but here are some tricks to tell some apart.
Stinkbugs and their relatives, the leaf-footed bug, are common pests with piercing-sucking mouth parts. Tomatoes are a common target.
Assassin bugs are predators in the garden, mostly feeding on small invertebrates. But they can bite humans, so give them space to do their work!
Context is key! Stinkbug and leaf-footed bug nymphs tend to be in large groups, while assassin bugs are typically solo or in pairs.
Predatory stink bugs, like this Euthyrhynchus floridanus, feed on other insects including caterpillars, beetles and more. Photo by Lyle J Buss, UF.
Non-predatory stink bugs, like this Nezara viridula, have piercing-sucking mouthparts, feeding on the liquid from fruits and leaves and damaging crops. Photo by James Castner, UF.
Check out the pointy shoulders on the predatory stink bugs. This is the easiest way to tell predatory (good bugs) from pest species (bad bugs) of stink bugs.
Fall webworms, Hyphantria cunea, are caterpillars that are present in the spring and summer too. They favor members of the cherry family.
Spiders, like this banana spider, Argiope appensa, are not insects but can be great predators in the garden.
Despite both making webs, these two 'bugs' are both beneficial to a garden. Birds and other predators will feed on the fall webworms, while the banana spider eats many pest species. Fall webworms rarely cause permanent damage to trees.
Integrated Pest Management (IPM)
IPM is a process to solve pest problems while minimizing risks to people and the environment. It focuses on long-term prevention of pests by managing the ecosystem.
Cultural IPM practices include:
Proper selection and maintenance of plants. Use resistant varieties, proper fertilization, proper irrigation, crop rotation, and insect barrier fabric.
Determining your level of tolerance. Is the insect damage reducing yield or a major aesthetic detraction in your landscape?
Scouting your garden often. Examine upper and lower leaf surfaces, as well as the soil, for eggs, larva, and adults. Hand picking mild infestations may be enough to control the pest.
Biological IPM practices include:
Encouraging beneficial insects. They are natural enemies of pests.
Using trap plants. Lure bad bugs away from your crop, such as growing sunflowers to attract leaf-footed bugs.
Chemical IPM:
Should be considered the last resort, as you do not want to disturb pollinators or beneficial insects. Always follow the label instructions carefully.
Start with natural products and spot treat the specific plant to target the pest you want to control. Most chemicals are not selective, so good bugs may be destroyed along with the bad bugs.
For caterpillars, try using Bt (Bacillus thuringiensis), which is an organic insecticide. It is most effective when caterpillars are small. Spray late in the evening, as this is when caterpillars actively feed, and Bt readily breaks down in sunlight.
Spinosad is another natural substance created by a soil bacterium that is used to control a wide variety of pests, such as thrips, spider mites, leaf-miners, mosquitoes, ants, and fruit flies. It can be found in many pesticide products.
You can try a homemade recipe for soft-bodied insects, but be careful not to use too much, as this can harm the plant. Always test on a section of foliage to check for phytotoxicity. Do not spray during hottest part of day, and cover top and bottom of leaves. If possible, apply when there is less sunlight during dusk and dawn to reduce chance of plant damage.
Recipe 1: Mix 1 teaspoon mild dish detergent (not with a degreaser) and 1 tablespoon of vegetable oil into a gallon of water.
Recipe 2: Add 2 teaspoons liquid soap (such as Ivory or Dr. Bronner’s) to 1 liter/quart or water.
There are other forms of chemical IPM, such as oil based pesticides. These include materials such as horticultural oils and neem oils, but many of these oils can burn the plant and kill beneficial insects, so be sure to read the label carefully and only apply as a last resort.
