We generally recommend using a pyrethroid such as Talstar P Professional Insecticide or Permethrin SFR as a preventative treatment in late spring/summer before egg hatch to protect trees. If trees are badly infested, then they should be removed and either chipped or burned.
Keep in mind that trees which become infested with bark beetles are almost always susceptible due to some other existing weakness such as drought or disease.
A good treatment of Talstar should help do the trick. However, if the junipers are really thick, then you need to apply quite a bit for the product to get down to the ground where the bees are nesting.
http://www.domyownpestcontrol.com/talstar-talstar-one-p-97.html
Talstar P should be mixed at 1 fl oz per gallon of water per 1,000 sq ft. We have never experienced an application taking 3 hours on a 100 X 10 or 50 X 20 area using a mist blower. Please take a few moments to review our treatment article on How to Get Rid of Mosquitoes for a successful eradication program. Please let us know if you have additional questions or concerns.
The rate for Talstar P in a hose end sprayer would be the same as if you were using in a pump sprayer, 0.5 to 1 fl oz (1 - 2 tbsp) per gallon of water for low volume applications, or 0.5 -1.0 fl. oz. per 1,000 square feet in a higher volume of water.
Yes, Talstar P is labeled for moths. The mixing rate is 1 fl oz per gallon of water. This can be used indoors and outdoors around the perimeter of your home. The residual is 30 days outdoors and 90 days indoors.
Talstar P (Talstar One) alone is good for perimeter treatment of general pests. For some pests you would benefit from mixing an IGR like Nyguard IGR with it. This prevents young insects (such as fleas, roaches, mosquitoes) from maturing into reproducing adults.