Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00000035
11/12/99
ACER INSECT PROBLEMS
Leaf stalk borer and petiole borer cause the same type of
injury. Both insects bore into the leaf stalk just below
the leaf blade. The leaf stalk shrivels, turns black, and
the leaf blade falls off. The leaf drop may appear heavy
but serious injury to a healthy tree is rare. Control
measures are usually not needed.
Gall mites stimulate the formation of growths or galls on
the leaves. The galls are small but can be so numerous
that individual leaves curl up. The most common gall is
bladder gall mite found on Silver Maple. The galls are
round and at first green but later turn red, then black,
then dry up. Galls of other shapes (Vis. 4) are seen less
frequently on other types of maples. Galls are not
serious, so chemical controls are not suggested.
Crimson erineum mite (Vis. 3) is usually found on Silver
Maple and causes the formation of red fuzzy patches on the
lower leaf surfaces. The problem is not serious so control
measures are not suggested.
Aphids infest maples, usually Norway Maple, and may be
numerous at times. High populations can cause leaf drop.
Another sign of heavy aphid infestation is honey dew on
lower leaves and objects beneath the tree. Aphids are
controlled by spraying or they may be left alone. If not
sprayed, predatory insects will bring the aphid population
under control.
Boxelder bug (Vis. 1) infests Boxelders, primarily the
female trees. The insect does no serious harm to the tree
but is a nuisance when it overwinters in homes. The insects
are red and black and can be vacuumed up when seen in the
house. Control measures include removal of female Boxelder
trees. If boxelders are growing in adjacent yards removing
your tree may not be effective.
Scales are an occasional problem on maples. Perhaps the
most common is cottony maple scale (Vis. 2). The insect
forms a cottony mass on the lower sides of branches. Scales
are controlled with dormant oil sprays applied in spring
before growth begins. Scales may also be controlled with
well-timed sprays to kill the crawlers.
If borers become a problem it is an indication the tree is
not growing well. Controlling borers involves keeping
trees healthy. Chemical controls of existing infestations
are more difficult. Proper control involves
identification of the borer infesting the tree then
applying insecticides at the proper time.
Related information.
Pesticide Recommendations
Aphids on Ornamentals
Maple Bladder Gall Mite
Crimson Erineum Mite
Cottony Maple Scale
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mentioned. This information becomes public property upon
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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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