While a few spittlebugs (Clasirptora spp.) won't doom your garden, these spit-wad-creating insects do suck sap from leaves, gradually weakening the host plant. During the larval stage, spittlebugs use the spit wads to protect themselves as they feed. Once mature, the 1/4-inch-long, dull gray-brown beetles continue to feed on plants without the protective foam cover. Spittlebugs show up on edibles, ornamentals and lawns, but with perseverance you can eliminate these insects from the garden.
Hand Washing Method
For a simple, nontoxic spittlebug solution, use a stream of water from the hose wash them off. This method is particularly well suited for minor infestations in small areas where you can monitor the site and follow up as new spit masses appear. Another nontoxic method to try is hand picking to remove spittlebugs. Start by wiping off the foam and then pluck and crush the larva underneath. Wash your hands with soap and water after working with any pest-infested plant before moving on to other garden tasks.
Chemical Control Method
For a chemical solution, use insecticidal soap spray for both larvae and mature spittlebugs. Mix 5 tablespoons of insecticidal soap spray concentrate with 1 gallon of water in a clean spray bottle or garden sprayer. Shake it up and then spray it directly on the spittlebugs. Follow up weekly until the spittlebugs disappear. Wear goggles and protective clothing whenever you're working with insecticides and keep people, pets and children away from treated plants until they dry thoroughly.
Do Nothing Approach
While it's true that spittlebugs damage plants when they feed in large numbers, this rarely happens. When you have only a few spittlebugs on a mature shrub or woody perennial and the foamy spittle isn't making your plants look awful, you can leave them alone. Natural predators, like parasitic wasps, pray on the larvae as they emerge, eventually restoring balance to the garden. Tender perennials and annuals suffer more severe damage from spittlebugs.
Favorite Host Plants
While spittlebugs aren't picky in their search for host plants they do have a few favorites. Annual beans (Phaseolus vulgaris) and strawberries (Fragaria x ananassa) which grow in U.S. Department of Agriculture plant hardiness zones 5 through 8, seem particularly attractive. You'll also commonly find them on lavender (Lavandula angustifolia) which grows in USDA zones 5 through 8 and rosemary (Rosmarinus officinalis) which grows in USDA zones 8 through 10.
Lawn Damage and Control
The two-lined spittlebug, a species that matures to a black-bodied beetle with horizontal red stripes, can infest and damage lawns. At the larval stage, it produces the protective spit wads during feeding. The larvae commonly feed down near the grass roots. Keep your lawn mowed and raked to discourage two-lined spittlebugs. Cutting back on watering as much as possible also helps control spittlebugs.
Insecticides for the Lawn
Spray the spittlebug larvae until they are saturated with a ready-to-spray insecticide that contains a pyrethroid. You can find insecticides specifically for lawns that attach to your garden hose. All you need to do is turn on the water and water the lawn. Apply insecticides in the spring and early summer or whenever the larvae are present. Keep children and pets off the lawn until it dries completely. While spraying, wear a respirator, eye protection and long pants and sleeves. Puncture the bottom of the insecticide bottle when it's empty and throw it away.