Most green industry clients perceive spittle as a negative thing, something to be avoided. In the case of the spittlebug, an infestation can be both ugly to look at and damaging to the plant material. Also called the froghopper, perhaps the best thing about a spittlebug is the name, both of which are certainly colorful.
PHOTOS BY JAMES KALISCH, UNL.
Fortunately, the protocol that has proven so effective for other turf and ornamental insects – integrated pest management – will help control spittlebugs and keep customers happy. As with other insects, the keys for success are identification, establishment of threshold, monitoring and consideration of all available pest control methods once the threshold has been surpassed.
Signs and symptoms
Normally, it is useful to distinguish between signs and symptoms when training your staff, especially if they are new to the industry. Generally, a sign is the visible part of the pest, while the symptom is the visible result of the pest acting on the plant.
A good example is a northern masked chafer grub in Kentucky bluegrass, where the symptoms are a generalized yellowing in a random, but patchy, pattern. The sign is the actual pest: the larval stages of the beetle, which feed on the roots of the turf plants. In the case of the spittlebug, the sign and the symptom are hard to differentiate from each other.
There are many species of spittlebugs. Saratoga spittlebugs and two-lined spittlebugs are common, but pine, juniper, meadow, dogwood and alder spittlebugs are important as well. Certain species habituate and feed on a regional basis only. The two-lined spittlebug is characterized by – you guessed it – two horizontal lines, or stripes, across the back on the wing covers. Depending on the light present and time of day, the stripes are red to tan. The remainder of the wing surface is black. As adults, they resemble leafhoppers, except they are a bit thicker and more round. When at rest, the wings are held at an angle forming a “V.” The adults are about 1/3 inch in size. In addition to the lines across the wings, a good identifying characteristic are the eyes, which are bright red in color. The abdomen is also red.
The nymphal stages resemble the adults, but are smaller and wingless. The nymphs are orange, yellow or white, with red eyes and brown heads. Nymphal stages produce the characteristic spittle mass, a white, bubbly or frothy material that envelops the nymph and provides protection from desiccation and predators.
Depending on the region of the country, there are usually two to three generations per year. There are four nymphal instars, and the life cycle requires about two months. Egg laying occurs at the base of the grass in the thatch in hollow grass stems, or behind the leaf sheaths. Eggs laid by the second generation overwinter and hatch the following spring, usually from late winter to early spring. First-generation adults are abundant in late spring or early summer.
Saratoga spittlebug nymphs feed on a variety of ornamental trees, shrubs and herbaceous plants. Adults are about .25 inch in size, oval, with prominent tan eyes. Nymphs are a bit smaller, greenish yellow and wingless. All stages of the insect feed on plants, creating the need to scout and monitor frequently, especially if a history of spittlebug damage has been established. Eggs hatch in late spring/early summer, with nymphs developing and feeding over the summer. Nymphal stages begin changing to adults in mid to late summer. Adults feed but do not produce spittle.
What to look for and how to look
In turf, you have to get down on your hands and knees and look into the turf canopy to find signs and symptoms of spittlebug feeding. Although both adults and nymphs suck juices from the grass with their piercing-sucking mouthparts, damage is caused primarily by the adults through the injection of phytotoxic salivary substances. Adults are most active in early morning and hide near the soil surface during the heat of the day. Knowing this habit is useful in order to schedule scouting and monitoring activities.
Feeding activity usually causes characteristic symptoms on turfgrass blades in the form of a purple and/or white stripe that runs along the grass blades of infested turfgrass. When heavily influenced by spittlebugs, the turf loses turgor and wilts, causing the tips to turn yellow, eventually brown, and then curl. Most spittle masses occur near the soil surface or in thatch, which is why they are not readily visible. However, some dried spittle masses may appear on grass blades during adult emergence. High moisture and humidity conditions favor their development. Typically, spittlebug numbers are higher during years with more spring and summer rainfall, or in turf that is maintained with abundant irrigation. Poorly adjusted sprinkler systems that apply more than the optimal amount of water to certain turf areas, but less than required to others, are a contributing factor. Thatch layers that are excessive also favor their development.
It’s usually easier to inspect for spittlebugs on ornamentals, as there is no turf canopy in the way, although not in all cases, as dense foliage can sometimes hide their presence. The telltale symptom to look for is the white spittle, present in early summer.
The main areas for success with cultural control of two-lined spittlebugs lie with thatch and irrigation management. Because the egg laying and feeding occur at the soil level or in the lower thatch, reducing the thatch layer will create a less hospitable environment for their growth and development. Consider all factors that lead to thatch buildup – cultivar tendencies, fertilization, pesticide usage, irrigation – and make adjustments accordingly.
Performing an irrigation audit will reveal the level of distribution uniformity of the sprinkler system. It is quite common for systems to deliver twice as much water in some areas as necessary. Systems with less than optimal distribution uniformity also contain areas of coverage that create dry spots. Human nature guides the irrigation scheduling (especially among homeowners) such that irrigation water is usually applied until the dry spots turn brown. In doing so, the areas where more than desired water is being applied favor the development of spittlebugs by creating a favorable microclimate. Overabundant irrigation also may lead to root rot, soil compaction and other problems.
Chemical control may be required to avoid significant injury in turf and ornamental plants, especially on turf and ornamental plantings with a history of damage. Be sure to select a product labeled for control of spittlebugs on the intended host – specific grass species or ornamental plant. In general, control will be improved if the turf is mowed and the clippings collected before application. Read the insecticide label thoroughly for other recommendations and guidelines.
Generally, liquid formulations are more effective than granular materials. Application in the early evening may be more effective, as the insects tend to be located higher in the turf canopy than during midday. Repeat applications may be necessary, especially for nymphs, as they are protected by the spittle mass, which reduces contact with the target pest.
Several products are registered for control, including bifenthrin (Onyx, Talstar, Baseline), carbaryl (Sevin), deltamethrin (DetalGuard T&O), lambda-cyhalothrin (Scimitar) and permethrin (Astro). Again, be sure that the product and host plant is on the label, as well as that the product is registered in the state where the application is being made.
John Fech is an extension educator specializing in turf and ornamentals at the University of Nebraska-Lincoln.