Knowledgebase

Magnolia Tree #470427

Asked July 14, 2018, 4:24 PM EDT

We have had a Magnolia Tree planted in our yard for the past 6 years and for the first time we have noticed a large amount of flies landing on the leaves of the tree. I noticed a shiny substance on the leaves and the flies seem to be drawn to it. My question is, do you have any ideal what may be causing the flies to swarm on the Magnolia tree this year or what the substance might be? Thank you. Regards, DJ

Ramsey County Minnesota

Expert Response

The tree has been affected by an armored insect called "scale." Magnolia scales deposit honey dew, a sweet waste product, that attracts ants and various flying insects including flies, wasps and bees.

This bulletin discusses magnolia scale and how to control them.
https://hort.uwex.edu/articles/magnolia-scale/
An Ask Extension Expert Replied July 14, 2018, 7:20 PM EDT
Please see attached picture. Could this be caused by the insect called "scale" as was listed above?
I started applying some Carbaryl to the tree and noticed the tree was covered with these.
Please advise and let me know if I need to do something else to prevent this from having this issue next year.
Thank you 
The Question Asker Replied September 26, 2018, 3:50 PM EDT
Yes, the disc-like spots are magnolia scales. The insects that are damaging the tree live under the protective cover (scale).

The application of Insecticides used to control magnolia scales must be precisely timed to be effective.

Learn more here:

An Ask Extension Expert Replied September 26, 2018, 8:54 PM EDT

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