Question

Webbing on Red Oak   QUESTION: We have found what we now believe to be bark lice on a Red Oak tree. The tree is located in Warrenville, IL. This is a suburb west of Chicago. We have an orange, powdery substance associated with the webbing. It is not slimy or wet. Have you even seen this? Do you think that the lice are feeding off this? I am sending some photos I hope help.

ANSWER: From the picture the orange dust looks like borer dust. The bark of oak is orange when you bore into it and if an insect entered the bark it would leave an orange dust. I would spray the area with an insecticide for borers one of the new ones is Merit. Check with your local nursery/garden type store for Merit or another insecticide for borers.

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QUESTION: You are right. The orange powder does look like frass. But there are no exit holes and the trees do not show any signs of borer damage. They are otherwise healthy. The orange powder is not only at the base of the tree but the underside of branches and on the trunk. To produce this much frass would take a lot of borers and would definitely cause a lot of damage to the tree. As a certified arborist it is my opinion this is not borer activity. The webbing has been attributed to bark lice in areas of the country down south. Thanks for your help

Answer
I have seen bark lice infestations here in Alabama many times but have not seen any frass associated with them. There are a couple of bark beetles  that when they bore into the bark could leave the frass. If it is a new infestation the exit hole would not be there. I suggest you contact the IL. State Forestry agency and ask one of their Foresters to take a look. The Chicago area has been hit with a couple of serious insect problems lately and you will want to rule these out. Here is the web link to their contact information.  http://dnr.state.il.us/conservation/forestry/

Since you are in the Chicago area you may want to contact the City Forester also. I found two contacts for them. This is the contact information for them.


CITY FORESTRY CONTACTS

Joseph McCarthy
Senior City Forester, Chicago
City of Chicago桞ureau of Forestry
312-747-2098
[email protected]



Karen Nowacki
Director GreenStreets
121 N. LaSalle, Room 406
Chicago, IL 60602
Phone: 312-744-7080