Purdue University
Agricultural Extension Service
Department of Entomology
Mimeo E-29
April, 1950
Rev. November 1953(2M)

HOW TO CONTROL SCALE INSECTS ON SHADE TREES AND SHRUBS

Scale insects are among the most common pests of shade trees and shrubs, yet they are easily overlooked and the dying of branches is often the first indication of their presence. Mature scales usually live on the branches of woody plants where they are firmly attached and never move. They suck the sap and also give off a sweet "honeydew" (plant sap passed through the digestive tract) which attracts ants and flies. A fungus often grows on this "honeydew" causing foliage on which it falls to have a sooty discoloration.
Young scales are known as "crawlers". They are mite-like in appearance, have legs and wander about over the plant for a period of time before they settle down and permanently attach themselves to the bark. There are over 60 kinds of scales known to occur in Indiana of which the following are the most important.

Kind of Scale	Trees Seriously Affected
Cottony Maple Scale.- A large scale usually attached to the undersides of branches. In the summer looks like strings of popcorn.	Soft Maple, box-elder and linden. Others affected occasionally.
Oyster Shell Scale.- Small grey scales about 1/8 inch long and curved to resemble ninature oyster shells. May completely ncrust branches.	Lilac, elms, soft maple, ash, poplar, dogwood, linden,willow, privet and hemlock.
European Elm Scale.- Oval-shaped red-dish-brown scales about 1/4 inch long surrounded by a white waxy fringe.	Elms of all ages.
Scurfy Scales.- 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 circular scales about the size of a pinhead, grey in color and with a center nipple. May completely encrust branches.	Apple, crabs, quince,mountain ash, flowering cherry and other trees and shrubs.
Terrapin and Lecanium Scales.- Large brown hemispherical scales which look like minature turtles.	Tulip, hickory, magnolia, oak and some evergreens.
Pine Leaf Scale.- Small elongate white scales attached to the needles of evergreen.	Pines and spruce of several species.
Juniper Scale.- A very small circular greyish-white scale with a yellow center found on the foliage and difficult to see	Juniper and arbor vitae.
Euonymus Scale.- Elongated brownish-grey scales and small elongated white scales found on foliage and twigs.	Euonymus and bittersweet.

Cooperative Extension Work in Agriculture and Home Economics
State of Indiana, Purdue University and United States Department of Agriculture Cooperating
H. J. Reed, director, Lafayette, Indiana
Issued in furtherance of the Acts of May 8 and June 30, 1914.