The first step in ridding the garden of an insect pest is to identify the culprit that is causing the damage. While highly distinct bugs, such as the preying mantis, are easy to distinguish, smaller, lesser known insects are a bit more challenging. A vast number of potential pests can plague a plant, but no single resource could possibly name them all, even when the color is a distinct, bright yellow. However, most garden pests are not unusual or exotic, which makes the task much simpler.
The Usual Suspects
Yellow bugs are not as common in the garden as green and brown ones, so the list of potential suspects is, consequently, much shorter. Aphids are tiny yellow bugs that can often be found taking cover on the undersides of leaves. Potato beetles are round, yellow and black striped bugs that tend to affect members of the nightshade family: potatoes, tomatoes, eggplants, petunias and so on. Cucumber beetles are oval-shaped insects that sometimes bear black spots or stripes. As the name suggests, they are commonly found on the leaves of cucumber plants, though they also attack squash, corn, beans, sweet potatoes, asters, chrysanthemums, zinnias and sweet peas. The juvenile version of the diamond back moth is yellowish in appearance, though it takes on a gray color as an adult. While it is not considered a serious pest, the diamond back moth does eat fresh foliage, inhibiting the plant’s ability to function. While these are the most common yellow insect pests, there are others. Should an unidentified pest become a serious problem, contact the local extension office for assistance.
Bugs are not necessarily a bad thing. The ugly, yellow insects covering the leaves of a prized plant may be beneficial beetle larvae dining on harmful scale insects. They could also be lacewings; their neon green color can easily take on yellow tones. Beneficial insects should be encouraged to take up residence in the garden, rather than being chased away, as they help reduce lingering populations of harmful bugs. For example, lacewings and their larvae feed on red spider mites, thrips, leafhoppers and aphids, effectively reducing the need for pesticides and insecticides.
While homemade bug sprays are not as potent as their commercial counterparts, they are less toxic and less expensive. That being said, to be fully effective, they may have to be applied several times. The first line of defense against most garden pests is an all-purpose insecticide. An effective homemade spray can be made by mixing 1/4 cup off 70 percent isopropyl alcohol into 3/4 cup of water. Transfer the solution to a plastic bottle, and spray the mixture directly onto any visible insects. Reapply the solution once every three days until the pests vanish. Should the alcohol prove ineffective, a stronger pesticide can be made from a combination of hot peppers, onions and garlic. To make this potent plant spray, place 2 hot peppers, 1 raw onion and 1 clove of fresh garlic in a blender with 1 qt. of water and blend until smooth. Pour the liquid through a piece of cheesecloth to remove any solids, and apply the remaining solution to the affected foliage; reapply the mixture twice a week until the insects are no longer apparent.
To prevent insects from invading the garden, cover young vegetables and plants with floating row covers. These lightweight sheets of fabric allow sunshine and water to reach the foliage and roots, but keep insects from landing on the leaves. Also, insects prefer the foliage of distressed plants and weeds. Keeping the garden watered, fertilized and weed free deters insects almost as effectively as multiple applications of insecticides.