Includes Tarnished plant bug (Lygus hesperus, L. elysus, L. keltoni)
Pest description and crop damage Adults (Order Hemiptera: Family Miridae) are less than 0.25 inch long and marked with a V-shaped or triangular mark on the back. Color ranges from light green to shades of brown or black. Nymphs are 0.04 to 0.25 inch long, green or yellow-green, with black spots on the back. Adults and nymphs damage plants by inserting their mouth parts into the plant tissue and sucking juices. Lygus are considered "cell feeders". Signs of damage include flagging of leaflets, leaves, or small stems. Adults and nymphs prefer to feed on the top third of the plant canopy.
Biology and life history Lygus species, such as the tarnished plant bug, feed on many different plants including weeds, crops, and native species. Alfalfa and quinoa fields often develop very large populations of lygus from which the insects may colonize hemp. Lygus can be found throughout the growing season and are common throughout the PNW. There are usually three or four generations each year.
Scouting and thresholds Lygus are easily found during normal scouting operations using a beating sheet/tray technique or with a vacuum sampler (i.e. inverted leaf blower) or by observing insect activity while walking through the crop. Both adults and nymphs of all sizes are likely to be present at the same time. There are no established treatment thresholds for lygus in hemp.
Generalist predators in potatoes such as Geogoris, big-eyed bugs, and Nabis, damsel bugs, are known to prey on lygus adults and nymphs. There are also braconid wasp parasitoids attacking lygus in the PNW.