Question
my question is:  Why do my roses all have flies on them? And they never have big flowers?


Answer
Here is an excellent web site that tells you how to grow bigger and better roses.
http://www.gardenersnet.com/roses/roses02.htm
Many times flies are attracted to the fertilizers in the garden. Any organic insecticide will solve your problem. You don't need a powerfull chemical to get ride of them. Hope this helps.