University of Vermont Extension
Department of Plant and Soil Science
Summer News
Article
THE LATEST
BAD BUG
Dr. Leonard Perry, Extension
Professor
University of Vermont
As if we didn’t have enough serious
invasive introduced (exotic) pests to watch for, such as the emerald ash borer
and Asian long-horned beetle, we now have another Asian import—the brown
marmorated stink bug. In the U.S. now
for over a decade, it has spread to 32 states.
First detection in Vermont was this year. It feeds on many fruits,
vegetables, and farm crops, either making them inedible or unsalable. This stink bug is a nuisance in homes as
well.
First detected in eastern Pennsylvania
in the mid 1990’s, this true bug likely arrived (as do many other exotic pests)
in packing material from Asia. Even in
its native China, Korea, Japan, and Taiwan it is an agricultural pest. This pest has caused widespread damage to
apples and peaches in mid-Atlantic states, and could cause similar damage in
other states. The apples end up with
many brown spots called “cat facing,” that makes them unmarketable. Other fruit
crops it damages with dead spots include other stone fruits like cherries, pear,
grapes, and brambles. Host vegetable
crops include corn, tomatoes, beans, cucumbers, eggplants, and peppers among
others.
Many ornamental plants also are
susceptible to this stink bug feeding including both trees and shrubs, ending
up with dead patches on leaves. These
bugs may feed on the main trunk and side branches for the sap. If you see wasps feeding on sap, look for the
bugs. Even flowers aren’t immune, with feeding reported on zinnias, snapdragon,
and sunflowers among others.
The adults emerge in late spring,
mating and laying eggs in summer. Look
on the undersides
of leaves for clusters of 20 to 30 light green, barrel-shaped eggs. Small black and red nymphs hatch, and go
through five stages before turning into adults.
Adults, like other true bugs, feed on plant sap with a beak consisting
of piercing-sucking mouthparts resembling straws. In early fall the adults search for
overwintering sites such as in buildings and other protected sites.
The adults are about 2/3-inch
long, patterned in shades of brown.
Similar to other stink bugs, their shield shape (wider at the rear) is
about as wide as long. Their differences
from other stinkbugs may not be obvious to the untrained eye so, to make sure,
consult your state university plant diagnostic clinic. These can be found online, including those
for Northeast states (www.nepdn.org). A
main difference from the common native stink bug is on the antennae. Look for alternating light and dark bands on antennae
of this exotic pest. More descriptions
and photos can be found online, including from Penn State University
(ento.psu.edu).
This stink bug is attracted to
warm home exteriors in the fall, and can enter through cracks and
openings. Inside, these bugs don’t harm
humans, but can be a nuisance flying about similar to Asian lady beetles and
cluster flies. When squashed or sucked into a vacuum, the foul odor released
makes their name obvious. This chemical
may cause a slight allergic skin reaction in some. To avoid this odor, vacuum a pleasant smell
such as potpourri (available inexpensively at many craft stores) first, or use
a shop vac already with some soapy water.
There are some pesticides that
can control this pest, but they are generally not recommended in homes and
gardens. Pesticides in homes can be
dangerous if misused, and spraying around cracks is temporary and ineffective
overall. Best is to seal any gaps or
cracks where they can enter and vacuum up any seen.
Pesticides for stink bugs in
gardens also kill good predator insects, if not pollinators too, resulting in
outbreaks of other pests such as spider mites.
By solving one problem you merely create
another. Best is to inspect plants for
the bugs often and regularly, knocking them off into soapy water. Researchers are working on biological
controls that will kill this pest and not predator insects and other native
stink bugs that don’t cause problems.
Being an introduced pest, no natural biological controls are present in
infested areas.
Although this bug can fly, and does
so moving from crop to crop through the season, it spreads longer distances mainly
through hitchhiking on materials moved by humans. If you’re visiting, or moving from, an area
with known infestations, make sure to watch for these bad bugs. Check vehicles, campers, packing materials,
or other objects that you’re transporting from outdoors during the growing
season, and from indoors during other times of year.
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