Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00001707
11/12/99

Aphids


Aphids are soft-bodied, slow-moving insects that reproduce
rapidly. Many aphids prefer to feed on young, succulent
growth (Vis. 1). Some feed in sheltered locations, such as
inside leaves that they have caused to curl or become
distorted. Aphids attack trees and shrubs of all kinds but
do not usually seriously injure them. New plant growth may
become distorted or stunted before predators and parasites
decimate the aphid population. The greatest damage may be
from the sticky, sugary aphid excrement called honeydew.
Honeydew may fall on automobiles or furniture below
infested trees. Sometimes a black fungus called sooty
mold (Vis. 2) will grow on the honeydew deposited on foliage
below aphid colonies.

Adelgids, psyllids or phylloxeras are closely related
insects that resemble aphids. The adelgids and
phylloxeras frequently induce infested host plants to form
galls in which the insects live.

Aphids are present on most plants, generally at
non-injurious levels. The honeydew excreted by aphids may
be useful for identifying aphid populations. Natural
controls, including natural enemies -- ladybird beetles,
lacewings, syrphid flies, parasitic wasps -- usually
bring aphid populations under control shortly after they
become noticeable. Before applying any insecticide
treatments, search the aphid colonies for these natural
enemies. High numbers of these beneficial insects usually
indicate that aphid problems are being controlled without
your intervention.


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