Scale Insects
SCALE INSECTS
WHAT THEY ARE
In one of the original Star Trek episodes, "Operation-Annihilate!" the crew lands on an outpost that had been decimated by an unknown plague. As they browse about, a flat, warty, flounder of a beast lands on the back of one of the crew members and begins to suck his life juices.
Perhaps this alien atrocity was inspired by scale insects that wreak a similar havoc on plants tissues?
Scale insects suck sap from the branches of trees, favoring fruiting plants, but also seen on others like oak and elm. Difficult to see because of their natural camouflage, they tend to appear at branch unions, sometimes in conjunction with ants that favor the honeydew they secrete as a sticky sap.
Affected branches will lose strength. Rubbing the branch with a fingertip will cause the scale to slide off and expose the soft underbody of the insect. Look for bumps and warty protuberances along otherwise smooth bark. More difficult to recognize on rough barked trees.
Younger scale insects (crawlers) are able to move around. As they age, the older females lose mobility, and after dying, their shell remains to protect the eggs (bottom left photo).
WHAT TO DO:
Affected areas should be cleaned by hand and then Insecticidal spray, or volck oil may be applied as a preventive measure during the dormant period.
FURTHER READING:
http://www.dgsgardening.btinternet.co.uk/scale.htm
