Roses covered with bugs

It is always a good idea to alternate between 2 types of sprays to prevent any resistance. Watkins Gild would be a good alternate spray. Something else to consider is whether the plants are becoming stressed, which makes them more likely to be unable to withstand pest / disease attack – consider their nutritional and watering requirements and whether these are being met, or overdone? If it is mites (you will see webs and the tiny spider like mites on the underside of the leaves) you should spray with Mavrik and Conqueror oil.