The tarnished plant bug (Lygus linalaris) is a true bug (order Hemiptera), with the crossed wings and piercing-sucking mouthparts characteristic of this order of insects. Commonly known as tarnish bug, or Lygus bug, it is an important agricultural pest. Adults are quick-moving, oval-shaped, light-green to brown bugs about 1/4 inch long. Forewings are black-tipped yellow triangles. Wings slope downward at the end. Nymphs are yellow-green and have five black dots. Eggs are long and curved. Adults emerge from debris in early spring and feed on fruit tree buds, then move to plants to lay eggs in stems and leaves. Eggs hatch in about ten days. Nymphs feed three to four weeks then molt. These bugs produce two to five generations a year.2
Being one of the top 10 economic pests in North American agriculture, the Lygus lineolaris has one of the broadest documented feeding range of any known insect. It feeds on more than 300 plants, almost a third of which are economically important crops in North America. Tarnish bugs are most abundant during the pre-bloom and blossom periods. Known as an apple pest since the 1860s, the tarnished plant bug causes fruit malformation that results in culling and downgrading of fruit. The bug’s fruit feeding is even more damaging to peach where overwintered and first-generation adults feed on terminal buds causing stunting. This injury is often referred to as “stop back.” Young fruit can drop prematurely, and injured fruit show scarred, sunken areas that become corky, hard, and lack fuzz. Such injuries are indistinguishable from that caused by stink bugs.1 On fully developed leaves, the injury appears as yellowish (chlorotic) spotting while on leaves injured in the bud stage or during leaf expansion appear distorted.
Insects that may be confused with adult tarnished plant bug include Calocoris plant bug, stink bugs and certain predacious bugs. Tarnished plant bug can be distinguished from most look-alikes by the presence of a yellow triangle in the center of its back.7
Tarnished plant bug is a key economic pest of strawberries with 2 to 3 generations per year. Fruit injury can occur from adult and nymph feeding. Tarnished plant bug feeding on strawberries can produce cat-faced berries. Their feeding kills the surrounding tissue and leads to small seedy strawberries that fail to mature (button berries).7
The tarnished plant bug can also affect yields of lima bean, green pepper, and tomato. It is considered an important or key cotton pest in the midsouth United States.
The Tarnish bug has few natural enemies (pathoges, parasites, or predators). Natural predators include Bigeyed bugs, damsel bugs, minute pirate bugs, and Peristenus. Peristenus are very small parasitic wasps about 2 to 3 mm long. They kill tarnished plant bugs during their reproductive cycle. Birds and lizards may eat these bugs, too.
Good garden sanitation is the primary method of plant bug control. This involves cleaning up all plant debris in the fall and elimination of weeds and if possible, legumes. Make regular observations from tight cluster stage to the first cover, particularly in orchard areas adjacent to weedy places or locations where alfalfa or other hay crops grow. Unbaited glossy, rectangular, non-reflective, white, sticky boards, hung low in the tree, are effective monitoring traps for plant bugs.4 Use sprays of garlic oil, or kaolin and plant oil products on large infestations. Cover plants with floating covers. Lygus bugs are most likely to damage fruit when nearby herbaceous vegetation on which they feed dries up or is cut, prompting the bugs to move into trees. Planting flowers and keeping nearby vegetation lush around trees will help to keep them away from fruit trees.
- Carl Walter Schaefer, Antonio Ricardo Panizzi – Heteroptera Of Economic Importance
- Howard Garrett, C. Malcolm Beck – Texas Bug Book: The Good, The Bad & The Ugly
- Steve H. Dreistadt, Jack Kelly Clark – Pests Of Landscape Trees And Shrubs: An Integrated Pest Management Guide
- Tarnished Plant Bug Fruit IPM Fact Sheet
- AgriLife Extension – Tarnished Plant Bug
- ScienceDaily – Biocontrol Could Help Manage Tarnished Plant Bug
- Tarnished Plant Bug (Lygus lineolaris) (mda.state.mn.us)