Basil Plant Bugs

Japanese Beetle

• The Japanese beetle is an invasive insect in the United States that feeds on hundreds of plant varieties, including basil. The beetle measures about 1/2 inch and has a metallic green color with brown wings. Japanese beetles feed on the tender section of leaves, but do not damage areas between leaf veins. This creates a lace-like or skeleton appearance to leaves. Infestation occurs in the warmer summer months between late June and August. Control for the Japanese beetle consists of handpicking the beetles and crushing them, or dropping them in soapy water.

Aphids

• Aphids are tiny insect pests that suck nutrients from basil leaves and stems, causing severe damage to the herb. Aphids measure about .125-inch long and range in color from green to black. Severe infestation symptoms consist of leaf curling, yellow leaves, reduced plant vigor and sooty mold. Sooty mold is a fungal disease caused when aphids secrete honeydew after feeding, which gives the sooty mold fungus an ideal growing medium. Low to moderate aphid populations rarely cause substantial damage and do not warrant control. However, control for severe infestations consists of spraying basil with water to dislodge the insects and insecticidal soap.

Spider Mites

• Spider mites are small arachnids that measure .02-inch and have a yellow-orange to green color. Spider mites, similar to aphids, suck nutrients from soft plant tissue. Symptoms of infection consist of chlorortic leaf spot, leaf yellowing, leaf drop and leaf webbing. Broad-spectrum pesticides and predatory mites are an effective method of control. However, be careful when using pesticides because they can kill predatory insects, which can increase spider mite populations.

Slugs

• Slugs are a type of gastropod mollusk that feed on basil foliage. Slugs feed during the nighttime and hide during the daytime in secluded areas, such as mulch. Symptoms of infection consist of visible slug movement on basil and large ragged holes in foliage. The Clemson University Extension recommends slug baits that contain iron phosphate as an effective method of control. Iron phosphate stops slugs from feeding on basil foliage and is less harmful to other insects, pets and birds than other slug repellents.