Black Grass Bugs Hitting Crested Wheatgrass

By PR Extension Office

“The little moisture received in the area has resulted in crested wheatgrass growing, which is good; but unfortunately, the black grass bug population has also exploded”, according to Mary Rumph, MSU Powder River Extension Agent.

“Most crested wheatgrass is being consumed by livestock as quickly as it appears, so the black grass bugs are competing with cattle or sheep”, stated Rumph. “In fact, one of the control recommendations is intensive grazing, so the pest may not be as prevalent this spring compared to some years”, she added.

“I noticed the first damage last week when there was an “anemic” look to the grass along the highway, especially on side slopes where the moisture was more limited,” said Rumph. The black grass bug literally “sucks the juices” out of the leaves, leaving a whitened, tough and stringy leaf. The black grass bug (labops hesperius) is one of the earliest pests to emerge in the spring and is able to feed in very cold weather. The young nymphs hatch from eggs that have been inserted into grass stems. The nymphs molt five times during their development into adults, feeding the entire time.

The insects aren’t regarded as too great of a threat unless they move into crested wheat hay meadows which they have been known to do in recent years, commented Rumph. The best control is done while they are still along the roadsides in a concentrated area. Local producers have found that low rates of malathion (1 to 1 ½ pints per acre) are effective for three to four years of control. The insecticide sevin is labeled for black grass bug control.

“They are fairly easy to kill,” added Rumph. The reason they are first seen in the ditches along the highway is due to the eggs laid in grass that wasn’t grazed heavily.

 

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