E-29
DEPARTMENT OF ENTOMOLOGY
ornamentals insects
SCALE INSECTS ON SHADE TREES AND SHRUBS
Donald L. Schuder, Extension Entomologist

Scale insects are comnon pests of shade trees and shrubs. More than 60 different kinds have been found in Indiana. Yet, scales are easily over-looked or ignored until tree or shrub branches "mysteriously" start to die.
Mature scales are usually found firmly attached to branches or foliage of woody plants and never move. They kill their host by sucking the sap, and
at the same time, give off a sweet "honeydew," which attracts ants and flies.
A fungus often grows on this honeydew when it drips off onto the lower leaves. This gives the leaves a sooty appearance.
Young scales are called crawlers.
They look like mites and wander about over the plant before settling down and becoming permanently attached to the bark.

COMMON SCALE INSECTS

Kinds of scale	Plants seriously afftected
COTTONY MAPLE SCALE: Large scales attached to the undersides of branches. In spring, when depositing eggs, the scales resemble strings of popcorn. The crawlers are found on the undersides of leaves.	Soft maple, box-elder and linden. Others affected occasionally.
OYSTER SHELL SCALE: Small, grey or brown scales about 1/8 inch long and curved like miniature oyster shells. May completely encrust the branches.	Lilac, elms, soft maple, ash, poplar, dogwood, linden, willow, redbud, privet, hemlock.
EUROPEAN ELM SCALE: Oval-shaped, reddish-brown scales about 1/4 inch long surrounded by a white waxy fringe.	Elms of all ages.
SCURFY SCALE: Small, dirty-white, pear-shaped scales not over 1/10 inch long. They lie very flat on the bark.	Most serious on young elms, apple, willow and dogwood.
SAN JOSE SCALE: Tiny, grey, circular scales about the size of a pinhead, with a center nipple. May completely encrust the branches.	Apple, crabs, quince, mountain ash, flowering cherry, and other trees and shrubs.
TERRAPIN AND LECANIUM SCALES: Large, brown, hemispherical scales that look like minature turtles.	Tulip, hickory, magnolia, oak and some evergreens.
PINE LEAF SCALE: Small, elongated, white scales, attached to the needles of evergreens.	Pines, fir, and spruce of several species.
JUNIPER SCALE: Tiny, circular, greyish-white scales with a yellow center. Found on foliage and hard to see.	Juniper and arborvitae.
EUONYMUS SCALE: Elongated, brownish-grey scales and small, elongated, white scales found on foliage and twigs.	Euonymus, pachysandra, and bittersweet.

COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA 47907