White bugs on tree branches dripping sticky honeydew #755449 - Ask Extension


White bugs on tree branches dripping sticky honeydew #755449

Asked June 10, 2021, 8:44 PM EDT

Our tree is heavily covered with these white scaly bugs dripping sap ,I think it is killing most of our branches I need to inject some thing with a needle into tree trunk , we have been trying many things ,stuff that we pour into the ground ,we’ve had a company come out and spray insecticide but this year is the worst, we need help, we need a product that we can inject into the tree that the bugs will eventually drink up and hopefully disappear, thank you,the Allan’s

St. Clair County Michigan

Expert Response


It sounds like you have a scale insect on your tree. Identifying which one determines how to correctly time treatment so that you kill the insects. Applying insecticide at the wrong time is not effective. 

So, can you please attach a clear picture of a branch with several leaves attached (from about 2 feet away)  and a picture of the whole tree from far enough back so we can see it( this might be 20 feet back or so) taking the picture in good light)

A picture of the white bugs would be very helpful, too.

If this is not possible let me know and we will give you a couple “best guesses” you can compare with what you see.

Laura Sheffer Replied June 10, 2021, 9:40 PM EDT

God bless you!                                                                                                 
Vickie J Alllan

On Jun 10, 2021, at 9:40 PM, Ask Extension <askextension@eduworks.com> wrote:

Vickie Allan Replied June 13, 2021, 6:34 PM EDT

Thank you, Vickie, and thanks for the pictures. This appears to be a maple tree? I can’t see any of the leaves clearly enough to be sure.

The scale insect looks like ‘cottony maple scale’ The tree may need two or more treatments to get control. https://www.canr.msu.edu/news/treatments_for_calico_scale_cottony_maple_scale_and_lecanium_spp._scales

A tree this size is best treated by a certified arborist, a professional who has taken training in care, diseases, pests and passed certification tests. He/she will come on site and give a complete diagnosis and a plant care plan.

Your tree has some branches that look like they may have died back, and this could be from a different issue, such as canker disease or a root problem. The arborist can determine what this issue is at the same time.

The arborist has the specialized equipment to spray large trees, which will help kill the insects now. The other advantage is the arborist can use products that will not affect beneficial insects as severely.

Select one of these professionals in your area, searching by zip code here-


If you decide to try and treat the scale insects yourself, you will not be able to stop the honeydew now. Instead you use a soil drench insecticide in spring or fall, which takes about 6 weeks to move through the tree. When the roots move the chemical through the tree, the insects will be feeding again. Purchase a product containing the active ingredient imidacloprid. Measure the circumference of the trunk 4.5 feet from the ground. Based on that measurement, you purchase enough Product to treat the tree.

As an example, for a tree that is 75 inches around you need anywhere from 37 to 75 ounces( see the product label) to treat the tree once. Mix it according to the label directions, and apply it in a circle around the base of the tree. This is done in the fall( about end of August) or spring( about Mid April). Plan to repeat this at least once, 12 months later.

Example products that can be used as a soil drench for scale insects are BioAdvanced Tree and Shrub Insect Control, Bonide Annual Tree and Shrub Insect Control, Spectracide Tree and Shrub Insect Spray.

MSU does not endorse any brands, but these are examples. There are other brands on the market that contain imidacloprid.

The products that are injected with needles are controlled chemicals that require a certified pesticide applicators license and special equipment. The arborist will have access to those, too.

I hope this helps with your tree.

Laura Sheffer Replied June 13, 2021, 11:07 PM EDT

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