Insect Hotline Issue 24


Acer with die-back caused by Japanese maple scale infestations.

mix of armored

Close-up of an Acer branch with gloomy scale (dark circular raised) and Japanese maple scale (brownish is the underlying skin after waxy white has been wiped or worn away).  Japanese maple scale are also the white kind of oyster shaped insect on the branch.


Close-up of an Acer trunk heavily infested with Japanese Maple scale.

Japanese maple scale

Close-up of Japanese maple scale on a Cornus trunk.  The brownish colored insects are the same scale, but where the white waxy covering has been worn or wiped away.  All pictures were provided by:  Brian Kunkel, Ornamentals IPM Extension Specialist, University of Delaware

Insect Hotline Issue 22


White prunicola or white peach scale on twigs of host.  Males cover the twigs and give the plant a ‘snowy appearnce’.

live f and m dead malefemale and cover

Close examination of an infestation (picture on the left) would reveal males (elongate and yellow), rounded and yellow, and dead male (dead from pesticide application; elongate and tannish brown). Picture on left is a close-up of the scale cover lifted off of a female white peach or white prunicola scale.

wps covered female with eggs WPS Gen2 Flipped20xB

Picture on left above is of a female laying eggs with the cover still in place.  Picture on right is same female but the scale covering (the ‘test’) removed.  All photos were taken by Nancy Gregory, plant diagnostician and Brian Kunkel, Ornamentals IPM Extension Specialist, University of Delaware

acrypt damage acryptmeria scale closeup

Picture on left shows banding on fir caused by Cryptomeria scale (photo by Brian Kunkel) and the picture on the right is a close-up of the infestation the undersides of the leaves (photo provided by:  Lorraine Graney, Bartlett Tree Experts,

Additional images from Mt Cuba

Armored scale are frequently some of the most difficult landscape pests to control.  Over the past several years Japanese maple scale has become more prevalent in landscapes and this insect pest feeds on many different hosts.  Included with this post are some images of Cornus florida with Japanese maple scale taken at Mount Cuba.  This insect pest has two generations a year for our area with eggs being found currently.  First generation crawlers should be out soon.  Scouting with double sided tape around branches with infestations is one way you can scout for crawler activity.  Other possible hosts include:  Acer, Chaenomeles, Cornus, Cotoneaster, Euonymus, Ilex, Prunus, Rosa, Syringa, Zelkova and many others.

Both images taken at Mount Cuba by Jimmy Testa