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Moisture encourages spittlebugs

Posted: July 28, 2012 - 11:17pm

Lately, we have been blessed with plenty of rain. I haven’t seen a July in a long time where the grasses and plants have looked so good.

But with the rain there are pest problems. One of these insects is more common in centipede than other grasses. The most common description of this insect is that I have a swarm of insects that fly up when I am mowing my centipede. This insect is the two-lined spittlebug.

The two-lined spittlebug (Prosapia bicincta) is a common pest of turf grasses. The adult spittlebug is about a quarter of an inch long and is black with red eyes and legs. It will have two red or orange lines across the wings. Spittlebugs will feed on all turfgrasses, but are more common in centipede. If injury is to occur on centipede, the damage will be from the nymphs feeding on the grass. The adults’ major host plant is hollies.

Both adults and nymphs feed on the plants by inserting their needle-like beaks into the stem and sucking out the juices. This causes the grass to yellow, wither and die if it goes unchecked. The symptoms are similar to the damage caused by chinch bugs, but spittlebug adults are much more mobile. The damage tends to be spread out, rather than be concentrated.

The nymphs are easily detected. Their distinctive spittle masses are on the grass stems near the soil surface. In the spring, these spittle masses can be found on the stems of verbena and many other plants. Adults fly readily when disturbed and can be flushed from the grass by walking through affected areas.

Early damage symptoms will look like yellow spots of dead or dying grass. With heavy infestations, these spots may overlap to form large areas of dead turf. So, how much spittlebug larvae does it take to damage the turf? The amount of damage will depend on how well the turf has been cared for. I have seen turf that has been damaged with as few as seven or eight spittlebug larva per square foot of turf. In my centipede, I have had as many as 15 to 20 per square foot and have seen no damage to the turf.

It’s been reported that spittlebug adults can damage a variety of ornamental plants, too, particularly during late summer and fall when populations are at their highest levels. The ornamental plants they prefer include hollies, asters and morning glory. On hollies, the damage can be seen as leaves that have small yellow spots on them. In severe cases, the leaves can be distorted.

If spittlebugs are a problem, there are several practices that can reduce their numbers. The first is to reduce the moisture level in the turf canopy. Spittlebug nymphs need high humidity to survive. They have the frothy substance around them to keep them from drying out.

There are several ways to reduce the moisture. One is to reduce the amount of water applied to the turf. Water deep and less often. The other way is to mow the centipede at the right height. The best mowing height for centipede is 1½ inches. This allows the crown of the grass to dry out and the larva can be killed.

The second way to reduce the moisture level is to reduce the thatch level. The thatch holds moisture and provides them with cover. Thatch can be reduced by aeration or topdressing with a good quality top soil, compost, or a sand/peat mix.

Spittlebug infestations can be controlled with several commonly available turf insecticides. This is more difficult to do because the nymphs are protected by the spittle mass. This covering can repel water. To get the best control, the insecticide must be applied with plenty of water. This volume is easily achieved with a hose-end sprayer.

Following good turf management practices can make infestations or reinfestations less likely.

Charles Phillips is a retired Columbia County Extension Service agent and operates Hort Consulting. Reach him at cphillipshort@comcast.net or at (706) 836-2152.

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