How to Identify Insect Pests

You may not find the slugs (and snails, which are slugs with a shell) but you'll definitely see the wet and slimy trail they leave behind. Slugs eat strawberries and just about anything else. 

If you see a sticky liquid or eaten leaves, it's time to take action in the garden. There are a few methods for treating slugs in your garden. You can hand pick them (wear gloves) and relocate them away from the garden. Setting up a bird feeder nearby may help, too. Copper slug tape wrapped around plant stems, non-toxic baits and diatomaceous earth will solve your slug problem as well. 

If you notice a sap-like, sticky liquid and a black, sooty mold on your plants, chances are your plants have aphids. Spotted yellow, distorted leaves and buds are also signs. 

Aphids suck juices out of plants and eventually kill them. This sticky mess also attracts ants and other insects. 

To get rid of aphids, first try spraying outdoor plants with a powerful watering spray nozzle attached to your garden hose until they're gone. If that doesn't work, prune away infested parts and discard. Leave enough foliage for your plant to survive.

If pests return, use an insecticidal soap or neem-based product and follow directions. These tips work for other pests such as scale and spider mites, too.

If you live in the south and southwest, mounds in the garden could mean fire ants. These mounds can grow as wide as 18 inches and as high as 12 inches. As they get taller, they begin to take on a dome shape. Unlike other ant mounds, fire ant homes typically don't have a center hole. make no mistake when you spot a mound.

Pouring hot water on mounds is a temporary solution. A more permanent fix is to use diatomaceous earth as a first line of defense. Neem-based products can also be beneficial for controlling fire ants. If organic methods do not work, try using a stronger fire ant killer for immediate control.

If one day your plants look beautiful, but the next, only leaves with veins remain, Japanese beetles could be the cause. This is a common pest on Rose of Sharon. To get rid of Japanese beetles, hand-pick and drop beetles into a bucket of soapy water. 

Organic neem-based products and insecticidal soaps also provide good control. Always use according to label directions. 

In worst cases, use Japanese beetle control with carbaryl, acephate and permethrin. 

Tomatoes may be the ideal plant for tomato and tobacco hornworms, but these pests have appetites for other vegetables and plants, too. Tomato hornworms, for example, will also eat peppers, eggplant and potatoes. These bright green caterpillars blend easily with your tomato stems and leaves but a keen eye will spot these pests.

Look for black margins on white stripes with a red horn for the tobacco hornworm. The tomato hornworm has green margins on its white stripes and a blue horn.

To rid your garden of these pesky pests, just hand pick and put hornworms in a soapy bucket of water. You can also sprinkle diatomaceous earth at the base of the plants, or use Bt early in the season (see next entry for squash vine borers). 

If you notice a sawdust-like substance piling up on the stems of your squash with little holes, you've got a resident squash vine borer inside the stem.

Squash vine borers will damage the inside stems of pumpkins (vine pictured above) and other squash. The damage comes when the larvae tunnel into the stems of squash, which can kill your plants. 

To get rid of squash vine borers, first try surgery. Take a small knife and cut a slit lengthwise near where you see the sawdust substance. When you locate the fat, white larvae, gently tug it out and feed it to the birds. Check other stems to ensure the damage is contained. To help the squash recover, cover the cut stem section with soil to promote additional root growth. 

If you don't find the borer, try injecting the infected stems with Bacillus thuringiensis, or Bt. Bt is an organic strain of bacteria that will eat squash vine borers and any other caterpillar.

If white-winged insects appear on the leaves of your tomatoes, these whiteflies need to be eradicated immediately, so don't waste time. They can leave a sticky residue on the leaves of plants and cause significant damage. 

To get rid of whiteflies, you can spray a steady stream of water on the plants to remove them. Then, prune away any damaged stems and spray the rest of the plant with insecticidal soap. Don't forget to spray the underside of the leaves.

If your cucumber vines suddenly look dry and brittle, inspect for cucumber beetles. Cucumber beetle species sport stripes, spots or bands. While picking off by hand is a great first option, planting nasturtium and dill companions by your cucumbers can provide additional plant protection.

For heavier infestations, use neem-based products.

If your roses have skeleton leaves, sawflies are likely the cause. Tiny rose slugs, the larval stage of sawflies, can cause significant damage. Some sawflies will chew holes through leaves. Get the problem under control early with a neem-based product.

Roses that are otherwise healthy can tolerate significant feeding damage and will usually put out new leaves by mid-summer.

Do you spy holes in your cabbage leaves? It could be hungry cabbage worms, or loopers chewing on your produce. Keep insects away from your cabbage by covering the plants with row covers or very lightweight cloth like tulle. Use stakes or hoops to hold the cover above the plants, and use clothespins to secure it in place. Bt can be effective at eliminating cabbage loopers, but you will need to spray frequently.

Aside from pollination, good bugs offer pest control. They eat bad bugs, reducing your need for chemical insecticides. Insects such as the lacewing, pictured above, ladybug, assassin bug, parasitic wasp, praying mantis, ground beetle, centipede and millipede are all predators of bad bugs. Read more about beneficial insects.

To attract good bugs, you’ll need to provide good living conditions. Grow plants they love such as mint, daisy, cosmos and clover. If all else fails, sacrifice a few tasty plants to draw bad bugs away from your garden. Plant them near the perimeter of your garden or yard. Learn more about attracting beneficial insects to your yard.