Aphids are little insects that usually appear in massive numbers. They attack new growth and suck the life from it, creating mottled, misshapen leaves. Sadly, aphids don't seem to discriminate much -- so watch for them on most plants.
The easiest, most organic way to stop aphids is to knock them off the plant with a stream of water from your garden hose.
The nemesis of broccoli, cabbage, cauliflower, and kales, cabbage loopers are green caterpillars that blend well with the plant leaves. They leave behind ragged holes in your otherwise lovely produce.
Use row covers in spring and fall to keep the pests from getting to your vegetables.
Keep an eye out for yellow-green beetles with black stripes or spots. Cucumber beetles are destructive pests that love pumpkins, squash, and cucumbers. They eat the leaves, flowers, and roots -- and spread disease.
Cucumber beetles can spend the winter hiding in the vegetable garden. Be sure to clean up all dead plants and leaves at the end of the season.
The scourge of many summer gardens, grasshoppers eat just about everything in their path when their populations rise. They come in a variety of sizes and colors -- and unfortunately all are equally hungry.
Plant marigolds, calendula, or sunflowers nearby to attract robber flies, which attack grasshoppers.
Does your lawn have brown patches that you can grab sections of and easily lift out? If so, grubs are probably at work under the soil. Randomly dig a few holes in your lawn and look for fat white worms that curl up in a C shape.
There are a number of grub-killing products on the market -- look for one at your local garden center.
Tomato hornworms look nasty -- these big green caterpillars have a distinctive spike (the "horn") on their backside and it takes just a handful to eat all the leaves from your tomato plant in just a few days.
It's easy -- and organic -- to pick the pests off your plants and drop them into a bucket of soapy water. Hornworms won't bite or sting.
These relatively large beetles (up to 1/2-inch long) have a metallic coppery sheen and a huge appetite. They've been making their way across North America, devouring more than 200 different plant species, their favorite being roses.
Spray the beetles with an insecticidal soap to stop them -- or at least slow them down -- the organic way.
Leaf miners make it look like someone took a white crayon and drew squiggly lines on your plant leaves. These little worms actually burrow tunnels through the leaf, causing the lines you see.
In all but the worst cases, leaf miners don't cause much damage. Pluck off affected leaves and worry about more harmful pests.
Sawfly larvae look like caterpillars or slugs, depending on the variety. They often feed in clusters, devouring the leaves on many trees and shrubs.
Look for a spray containing the ingredient spinosad; this is a natural product that's often effective on sawflies.
If you see gray bugs on your squash, cucumbers, or melons, watch out -- they're probably squash bugs, a common pest that sucks plant nutrients from the leaves and can spread a number of diseases.
Several beneficial insects, including tachnid flies, attack squash bugs. Include flowers such as marigolds, calendula, sunflowers, or dill in your garden to attract the good guys.
Fall doesn't mean the end of pest problems in the garden -- it marks the entrance of fall webworms on the scene. These caterpillars make big nests that look like webs in the leaves of trees and shrubs.
Remove the webbing with a long-handled shovel or rake, or use a big stick. Once the webbing is gone, the caterpillars are easy prey for hungry birds.
One of the most common plant diseases in the world, powdery mildew looks like someone sprinkled gray or white powder on a plant's leaves. As the disease matures, it creates leaf spotting and eventually your plants' foliage turns yellow and dies.
Some plants are more resistant to the disease than others. Choose resistant varieties whenever possible to keep powdery mildew out of your garden.
Black spot looks like what it sounds -- black spots (ringed in yellow) appear on your plant leaves and eventually kill them, turning your beautiful, prize-winning roses into a landscape eyesore.
Stop black spot by keeping your roses' foliage dry. Wet leaves -- especially in the afternoon or evening hours -- encourage this and other fungal diseases.