Magnolia Scale Treatment – Timing is Everything

Our customers have noticed that we are starting treatment for Magnolia Scale later than usual this year. In the past, we generally the first application occurred in late September. We based our application timing on everything we had read and were told by leading entomologists who study the lifecycles of these insects.

‘Scale insects’ are very difficult to control in general but especially Magnolia Scale. Instead of going with the conventional wisdom for when to treat these trees in our temperate zone, we decided to get a little more scientific.

If you really want to know what our game plan is, and why, please read on.

The Life Cycle of Magnolia Scale

The white and grey pods that you see on the branches of trees were created by a single female Magnolia Scale adult. She formed that pod in the Spring, stayed inside it all Summer before giving birth to hundreds of baby crawlers. Once she gives birth, the female adult dies within the pod. These baby crawlers are almost microscopic when they hatch and live within the pod, feeding off of the carcass of the deceased female. (We know, kind of graphic). The crawlers will slowly begin to emerge from the pod late Summer through early Fall.


photo courtesy of Joe Boggs

This had us wondering; How long does it take for all of the crawlers to emerge from within the pod? A few days, a week or a month? Since the insecticide sprays will work best if we spray once ALL of the crawlers have emerged, this seemed like an important thing to know. None of the experts that we talked to seemed to know the answer to that question.

So, Tree Green purchased a powerful microscope of our own to see exactly what was going on with these crawlers first hand. We noticed that some of the crawlers were indeed out from their pods in August and we wondered if we actually needed to start spraying earlier than we had in prior years. Once we flaked some of the pods open however, you could see under the microscope that there were still more crawlers concealed beneath the pod. Then we re-checked every week and to our surprise there were still crawlers feeding within the pods.  Our most recent check was the other day, October 3rd. Granted there were fewer crawlers under the pods and had we sprayed, some would have been protected.

Photo: Rutgers Cooperative Extension

Photo: Rutgers Cooperative Extension

Once these crawlers emerge from the pods, we are told they do not go back inside. They live on the tree or travel to other area Magnolia trees. The crawlers go dormant when temperatures drop below freezing over the Winter. Once Spring comes, the baby females grow, mate and begin making those pods all over again, repeating the cycle.

We are waiting until our microscope tells us that most, if not all of the crawlers, have emerged. There are many factors that could influence emergence however. Certain neighborhoods may be affected differently from others and tree exposure to sun and shade is different from property to property.  We are doing our very best to monitor these insects and take into account these varying factors to choose the best time to begin spray applications.

Insect and disease control is not an exact science so one year might be different from the last. This year we might start in mid-October and next year, late September. The type of Spring, Summer and Fall that we have changes from year to year, and with that, so changes the cycle of living organisms.

We know of no other company who takes the measures that we do to ensure the best possible service delivered at the most opportune and effective times. We pride ourselves on that fact and thank you for continuing to trust Tree Green with your tree care!

Magnolia Scale Causing Damage

magnolia scale magnolia with white spots - scale

We realize that there are many different types of Scale insects, but by far Magnolia Scale is the most prevalent these days.

This year, we are getting inundated with phone calls from homeowners whose magnolias have Scale. Their trees are developing blackened branches and leaves, and the shrubs, perennials, concrete, decking and deck furniture under them are also turning into a black, sticky mess. A black fungus called ‘Sooty Mold’ develops and grows on anything the dripping sap lands on.

These insects are sucking the moisture and nutrients out of these trees; and left unchecked, this can result in the death of the tree.

This problem will only worsen year to year as the insects will mate this Fall and leave behind Scale offspring which will overwinter and spread heavier again next year.

Check the undersides of your Magnolias branches. If you spot this Scale, give us a call. We would be happy to stop at your home to inspect your trees and leave you more information regarding treatment and pricing.

Insect Problems for Western Suburbs’ Trees

You might think that the bitterly cold and harsh winter would affect the insect population in our area.  Yet, it appears the cold winter did not affect insect populations at all. We are actually seeing increases in insect activity.

What to look for? Many insect problems result in sap dripping from your trees.  If your car windshield, deck, patio furniture or kids toys are sticky, you have insect problems. If you see shiny spots of sap on leaves on the lower portions of a tree, or even if your grass feels sticky as you walk on it, you have an insect problem which can be quickly and easily rectified.  A few examples include:

Locust Plant Bugs. If you have a locust tree, and the younger leaves at the ends of the branches are curling and browning slightly, you have Locust Plant Bugs. When you sit on your deck or patio on breezy days and your head is itching, you might see tiny, bright green bugs on your arm.  Those are Locust Plant Bugs.

locust trees
The Locust on the left is under our care. The locust on the right is not.

Magnolia Scale Pods on Magnolia, Cottony Maple Scale Pods on Maples and Lecanium Scale Pods.  These different pods all contain insects that are protected within the pods. These insects have one thing in common; they suck the sap from the tree, weakening it, and their bodies excrete a sticky honeydew which drips from the pods, causing sap drippage.  Later, when the insects emerge from the pods, they excrete the same sticky honeydew from their bodies.
lecanium scale pods on crab tree
This photo shows Lecanium Scale pods on a Crab tree.  They appear to be tiny bumps on the branch that looks like lady bugs.

Examples of other Scale pods can be viewed here. These are just a few examples of what you might notice on your property this year and in years to come. Treating trees for these problems can be extremely effective, but only when using the most effective insecticides along with proper timing. Spraying too early, before the insects emerge from the pods, will have no effect on them.

Tree Green wants to work with you to assure the health of your trees.   Please call our office at 630.668.4350 or email us  if you notice an insect problem or other situation affecting the health of your trees.  A Tree Green Arborist will be out to explain what is going on.