Download Plant Bugs on Perennials and Landscape Shrubs

Plant Bugs on Perennials and Landscape Shrubs
(fourlined, tarnished and phlox plant bugs)
Fourlined plant
bug adult.
Tarnished plant bug adult.
Fourlined plant bug
Fourlined plant bug damage nymph.
to leaf.
Species: The fourlined plant bug,
Poecilocapsus lineatus, is the most common
plant bug pest encountered in perennials and
landscape shrubs. The tarnished plant bug,
Lygus lineolaris, is another generalist plant
feeder common in landscapes. Other plant
bugs usually have very narrow host plant
ranges, such as the phlox plant bug, Lopidea
davisi, yucca plant bug, Halticotoma valida, and
hollyhock plant bug, Brooksetta althaeae.
Distribution:
The fourlined plant bug is found east of the
Rocky Mountains, and tarnished plant bugs
inhabit all of North America. The other species are usually found wherever their hosts are
cultivated.
Hosts:
Fourlined plant bugs have been found on over
250 species of plants in 57 families; tarnished
plant bugs have been found on over 380 hosts!
Most of the other species prefer single host
plants or restrict their feed to a single genus or
family of plants. In typical urban landscapes,
the fourlined plant bug damage is most commonly found on perennials (especially those
in the mint family or composites), but they commonly attacked shrubs including: azalea, dogwood, forsythia, viburnum and weigelia. The
tarnished plant bug seems to prefer plants in
the aster and rose families.
Damage:
Most plant bugs appear to insert their mouth
stylets into host plant tissues and inject a tissue dissolving saliva. They then suck out the
liquified plant tissues. This produces a typical
sunken lesion which can be circular or angular, depending on the host plant leaf structure.
Feeding on immature leaves can cause considerable leaf distortion - cupping, twisting and
crumpling. Occasionally, the lesion spots dry
and fall out, producing small holes in leaves.
Description and Life Cycle:
Plant bugs have the characteristic “bug” shape
- elongate oval bodies with a diamond-shaped
zone on the posterior where the wing mem-
branes cross, and a pentagonal-shaped pronotum
(the area just behind the head). All have long antennae and long legs. They run and often fly when
disturbed.
The fourlined plant bug is yellow-green with four
longitudinal black stripes down the back. However,
the nymphs are a bright crimson red with black wing
pads. The tarnished plant bug adult is a mottled
tan and brown and the nymphs are usually greenish. The phlox plant bug is a reddish-orange color
as is the yucca plant bug. The hollyhock plant bugs
are green.
Most plant bugs appear to spend the fall and winter as eggs inserted into host plant tissues, but the
tarnished plant bugs overwinter as adults hiding in
leaf litter. The fourlined plant bug has one generation per year with nymphs hatching in April to early
May, and new adults appearing by late May and
early June. The other plant bug species usually
have 2 to 4 generations per season. Damage is
most severe when the nymphs are feeding on developing plant tissues in the spring.
Control Hints:
Most plant bugs are considered aesthetic nuisance
pests since they rarely kill their host plants. However, leaf and flower distortion can be very severe
and can greatly reduce the aesthetic value of landscape plants.
Option 1: Cultural Control - Destroy Overwintering
Eggs & Habitat - Since the eggs of most plant bugs
are inserted into host plant tissues by the fall, cut-
ting and removal of dead plant stalks of perennials
can reduce plant bug innoculum for the next season. Be sure to bury or compost removed plant
material or remove residues from the landscape
area. Remove leaf litter and reduce mulch thicknesses to eliminate areas where tarnished plant
bug adults can overwinter.
Option 2: Cultural Control - Hand Crush Nymphs
or Syringe - In low populations, the small plant bug
nymphs can be located within host plant leaves
and crushed. Be careful to cup you hands around
affected leaves since the nymphs will quickly run
or drop from the plant. A hard spray of water, syringing, can often knock plant bug nymphs from
their host plants and these nymphs often have difficulty reestablishing on their hosts.
Option 3: Chemical Control - Soaps & Oil Sprays Plant bug nymphs are very easily destroyed by insecticidal soap or horticultural oil sprays, but the
nymphs have to be contacted with the emulsions.
Be careful when using soaps or oils on perennials
that have set flower buds or are flowering as phytotoxicity can occur.
Option 4: Chemical Control - Insecticides - Both
contact and systemic insecticides are effective for
control of plant bugs. Applications of contact
insecticides, e.g. pyrethroids, should be made as
soon as the first sign of nymphal bug feeding is
noticed. Since many soil applied systemics require
several days to weeks to be absorbed, apply these
several weeks before plant bug nymphs are
expected. This will help reduce plant distortion.
Revised 05/2003; © D.J. Shetlar
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some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in
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