Insect scale, or tree scale refers to a fast multiplying, sucking insect that comes in a many varieties. They actually don't even look like insects in the way you might think. For one, they don't move. Nor do they have visible legs.
They attach themselves to the leaves and needles of trees, plants and shrubs, sucking out the sap with devastating impact. Left untreated, trees can become so severely depleted that death is inevitable.
The scale insect will feed on the sap of the host tree, causing the leaves or needles to turn a yellowish brown. Another symptom would be the obvious presence of this easily identifiable insect. We often see both the hard shell and cottony softy varieties.
Sometimes we get calls from people saying their tree is leaking sap on their car. Sap can leak from trees for many reasons and there are a variety of wood boring insects that can cause sap to drip.
However, in the case of tree scale, the insect will secrete a very sticky substance known as "honeydew" and that's the sticky "tree sap" that gets on your car.
We run into scale a lot in Westchester. We se it on on pine, spruce, hemlock, douglas fir, cedar and host of other plants, including fern, boxwood, holly, honeysuckle and pachysandra.
Dormant horticultural oil spray is the best treatment for Scale. It's natural and it doesn't hurt the tree but will suffocate the insect. It can be applied during the tree's dormant season to kill off insects such as scale, aphids and mites.
In lighter concentrations, horticultural oils can also be applied during the growing season. Although, there are many factors that need to be considered, including temperature, humidity and known plant sensitivities. For this reason, it's in your best interest to consult with a professional.
Horticultural oils are also generally thought to be safe for humans and pets, which is why they are often used on fruit baring trees.
When you sign on for our tree and plant health care program, we'll address insect issues before they become problems.