PLANT HEAL
ANT HEALTH CARE All photos provided by Rainbow Treecare Scientific Advancements Lecanium scale
Scales
Weighing in on
By Br andon Gallagher Watson Scale insects are important pests of shade trees,and,as many practition-
ers will tell you, they can be challenging to manage.Their diversity, cosmopolitan dining tastes,and staggering reproductive rates are partly why they have a reputation as being difficult,but by understanding a few key points about scales,you can set the expectations and offer these services with confidence.
The sheer scale of it all With 8,000 recognized species, scales are found pretty much every-
where.Most make their living as plant parasites, and can be found on thousands of different plant species.The scale insects are also very diverse in their appearance.Some are quite large — up to 1/2 inch in diameter —while others are barely visible without magnification.They can have complicated and varied lifecycles, with at least nine different types of sexual,hermaphroditic,and even parthenogenic reproduction strategies that would take you all day to Google and still never fully understand.
14 Arbor Age / April 2012
A single female can lay upwards of 4,600 eggs per brood and have two to three generations in a year, so,suffice to say,however they get it done, it seems to be working.
The males and females can look very different from each other and
the nymphs can look very different from the adults.They can be shiny, spotted,waxy, dull,showy,drab,smooth or sticky.Commonly,they cover themselves with a protective layer that gives them the appearance of being fish or reptile scales on twigs and leaves, which gave rise to their common name, scale insects. There are currently 48 families of scale insects classified in the
superfamily Coccoidea, but arborists are mostly concerned with just two of these families.The Coccidae,which we refer to as soft scales, and the Diaspididae,which are the hard, or armored scales.There are other frequently seen scale cousins, such as mealy bugs and cottony cushion scales,which are not in either of these families,but most prac- titioners just lump them in with the soft scales as their management is
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