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University
of Rhode Island GreenShare Factsheets
Tarnished
Plant Bug
Llygus lineolaris
Hemiptera: Miridae
The tarnished plant bug is a common pest on numerous vegetable,
fruit and flower crops, as well as a number of weeds. It is
found throughout the United States, and attacks over 500 commercial
crops. Vegetable hosts include bean, beet, cauliflower, cabbage,
chard, celery, cucumber, potato, turnip and dill; fruits include
apple, peach, pear, strawberry and most other deciduous and
small fruits. It also attacks many flowers including dahlia,
aster, calendula, chrysanthemum, cosmos, gladiolus, poppy,
salvia, daisy, sunflower, verbena, zinnia and others.
The tarnished plant bug is a true bug (order: Hemiptera),
with the crossed wings and piercing-sucking mouthparts characteristic
of this order of insects. The piercing-sucking mouthparts are
inserted into the plant tissues, concurrently introducing a
toxic saliva into the plant and feeding. This pest causes various
types of injury, including deformed leaves (as in beets and
chard) and scarred, discolored stems or leaf petioles. In a
number of fruits, the buds of the developing fruit are dwarfed
and pitted. The tops of dill plants are often killed and blackened
above the feeding wound.
The tarnished plant bug is a small, flattened bug, about
6 mm (1/4 inch) long, generally brown in color, and mottled
with splotches of white, yellow, reddish-brown and black. Tarnished
plant bugs develop through five nymphal stages. The nymphs
are very small and greenish-yellow, marked dorsally with four
black dots on the thorax and one on the abdomen. Like the adults,
the nymphs have piercing-sucking mouth parts and feed on plant
tissues. The wings of the adults have a hard wing cover similar
to that of a beetle with a smoky-brown membranous tip. The
adults will fly readily when disturbed.
The adult bugs hibernate among weeds, leaves and bark
through the winter. They emerge early in the spring and fly
to host plants to feed, later migrating to other plants to
lay eggs on the leaves or flowers. The life cycle is completed
in approximately three to four weeks, and there are from three
to five generations per season. By midsummer there may be great
numbers of tarnished plant bugs present, but they are well
camouflaged and often go unnoticed.
Tarnished plant bugs can be difficult to control. Cultural
control practices include the removal of weeds and the elimination
of trash and other debris which could provide overwintering
sites. Mowing grass and weeds around gardens may also help
to reduce breeding sites. Verify that insecticides are labeled
for use on the tarnished plant bug and follow label directions
carefully.
Adapted from G.R. Nielsen,
University of Vermont Extension, 1999
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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