Magnolia scale/wasps treatment in Toronto

My magnolia tree seems to be emitting a type of sap. It gets all over my car, especially on my windshield. A large number of wasps have started gathering around these sappy excretions and it is getting dangerous out there.
I've read that the sap is actually an excretion of a bug, the magnolia scale, that infests magnolia trees. I have noticed a little bit of white bumby areas on some branches but nothing alarming.
I know there are some insecticide sprays that can be applied to the tree at certain times of the year to help combat this problem. But I fear that applying this stuff will be beyond my skill/commitment level.
So, does anybody out there know of a company in Toronto, Canada that specializes in this type of pest control?
I used PCO last year for something else but was not completely satisfied with the results.
What type of company should I be looking for, a pest control company or a landscaping oriented company?
Joey Goldstein
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