Read and follow all labels associated with the product you are using. There are many different options when it comes to safe practices as a homeowner. It should be known that a lot of the chemicals we use can be purchased and applied by homeowners. The key is to first properly identify the pest, have a targeted approach, and properly select what insecticide is best for the situation.
The best option for homeowners is an imidacloprid that is applied systemically through Basel drench (meaning mixed in a bucket and poured at the base of the tree). While this is a common DIY method, our professional preventative insect and mite treatments use higher-grade products and more precise application methods to protect your trees without over-applying chemicals to your soil.
Here is a link to the best option that can be purchased at most large retail stores. Name of the product is BioAdvanced Tree and Shrub Protect and Feed. It comes in a blue bottle and can be purchased at most large retail stores. This insecticide is broad spectrum, meaning it kills beneficial insects as well and can harm honeybees. Please read all instructions and time properly!
If you are dealing with more aggressive pests like conifer killers, you may need a specialized bark beetle treatment that penetrates deeper than standard retail products can.
Link to general use insecticide product mentioned.
Link to Armored Pine Scale Treatment Must be combined with non-ionic surfactant ***