Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00001607
11/12/99
House Plant Pest Problems
House plants can develop many problems but most have
environmental or cultural causes. If something is
actually attacking a house plant it is usually an insect.
Diseases are not common on most house plants.
Insects most often encountered are mites, aphids,
mealybugs, scale, whitefly, and various soil insects.
Some pesticides which control insects are harmful to the
plant. Be sure to read the pesticide label and follow all
instructions. Any single pesticide does not usually kill
all pests and repeat applications are usually necessary.
Mites or spider mites are hard to see. They are extremely
small and a magnifying glass is usually needed to see
them. Plants infested with mites lose their green color
and appear bronzed or washed out (Vis. 1). In severe cases,
the mites will form a fine webbing that may cover all or
part of the plant. Once a plant is infested with mites,
control will be difficult. Mite infested leaves may have
a gritty feel, or look like they are covered with a fine
coat of ashes.
Aphids are common on house plant insects but fortunately,
are easily controlled. Aphids suck sap from the plant and
can cause new growth to be distorted. Aphids are found on
new growth and the undersides of the leaves. Heavy
infestations cover the plants with a sticky syrup called
honeydew. Aphids can be controlled with most commonly
available house plant insect sprays.
Mealybugs look like little white tufts of cotton so are
often mistaken for a disease. They are normally found on
the undersides of leaves or on stems at the point where a
leaf joins. The white, waxy coating protects the insects
from sprays, making control difficult. Add 1/2 teaspoon
of household detergent to each gallon of spray solution
to ensure the mealybugs are wet.
The adult whitefly is a small white "fly" while the
immature stage is scale-like and doesn't move. Moving
infested plants causes the adults to fly away.
Controlling whitefly is difficult and repeated sprays will
be needed. Avoid plants such as fuchsia that are favored
by the insect.
Scale insects often build up to large numbers because they
go undetected. Their shell protects them from pesticides.
Scales are usually found on stems and the undersides of
leaves but can be on top of the leaves. Small
infestations can be removed by touching each insect with a
cotton swab dipped in alcohol.
Soil insects are noticed when brought to the surface
during watering. Adults and larvae of several insects may
fly or crawl around on the soil surface. In most cases
they do no real harm to the plant. Large populations can
cause wilting and poor plant growth due to minor root
pruning. Unfortunately, pesticides used to control soil
insects may be as harmful to the plant as the insects.
House plant diseases are not seen as often as insects.
Diseases such as powdery mildew or various root and stem
rots are encountered, but can be controlled to some extent
with proper plant care. Most problems resembling diseases
are the result of improper care.
This information is for educational purposes only. References
to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not
mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU
Extension. Reprinting cannot be used to endorse or advertise
a commercial product or company.
This file was generated from data base ZZ on 01/19/00.
Data base ZZ was last revised on 11/12/99.
For more information about this data base or its contents please contact
heatley@msue.msu.edu . Please read our
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