Tarnished plant bug (Lygus bugs)
Lygus lineolaris (P. de B), L. hesperus Knight
(Hemiptera: Miridae)


Adults are about 6 mm long, oval, and rather flattened. They are yellowish to greenish brown, and have dark markings on their wings. The immature forms are pale green and look similar to an aphid. They can be distinguished from aphids by their more rapid movements.

Biology and damage:

The piercing-sucking feeding by Lygus bugs are one of the causes of irregularly-shaped, catfaced strawberries. The insects damage fruit by puncturing individual seeds; this, in turn, stops development of the berry in the area surrounding the feeding site. Straw brown seeds that are large and hollow are a good indication of lygus bug damage.
There are 3 to 6 generations of this pest each year (Davidson & Lyon 1987). Adults become active in early spring and deposit their curved eggs into stems, and leaf midribs. Egg hatch takes place about 1 week later depending on temperature, and the green-yellow nymphs progress through 5 instars, reaching the adult stage in approximately 30 days.
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Field scouting/monitoring:

One method of field scouting involves shaking flower clusters over a sheet of white cardboard (Cooley & Schloemann 1990). An action threshold of 1 nymph per cluster is recommended. Penn (1991) suggest a threshold of 20-25 TPB per 50 clusters. Other scouting methods have been implemented in California. Threshold levels have been developed for lygus bugs depending on monitoring method used. When the beat sheet (12 inch embroidery hoop with muslin) is used, sample one plant in each 20 ft of row by placing the beating tray under the plant and beating it with your hand. Apply sprays when 1 lygus nymph is found in 20 plants. The Allen-vac is a more efficient sampling device, and sprays should be applied when you find 1 lygus/10 plants.



Virginia home spray guidelines
California guidelines


Predators that feed on the nymphal stages of lygus bug include bigeyed bugs, Geocoris spp., damsel bugs, Nabis spp., minute pirate bugs, Orius tristicolor, and several species of spiders.

Control weeds along roadways, ditches, and field borders to help prevent spring buildup of lygus bugs. Overwintered lygus bugs lay eggs in weeds in January and they hatch in March. Weed control should be carried out in March and early April while lygus are still nymphs. Once adults are present on weeds, they will migrate into strawberries when the weeds are removed. To avoid adult migration in spring, mow or disc under cover crops, especially legumes, before they flower and while lygus are still in the nymphal stages.