That is correct, the spray will not hurt the plant. I agree with Swamper. Spray the entire plant, I even spray the roots. That will solve your problem. :-)
Just a quick question about thrips, can they be seen by the naked eye?
Also, I have a few spiders around my cymbidiums, I try to take down their webs frequently. Would spiders be good to keep away the aphids and thrips?