I'm guessing that they are the nymphs of the leaf footed stink bug, but there are assassin bug nymphs that look very similar. If they are leaf footed bugs, you don't want them in large numbers.

Here is a link that might be useful:

thanks so much, rhizo - you are right - Leaf footed bugs and they really are ugly. I hope I can eradicate them but i have no idea if I can. My garden borders are huge (I surrounded my house on three acres, so it will take me at least three days to check all the plants). I hope I have good luck - thanks

Carrie

You might want to return to that other forum where you posted this question....just so that the others know that this isn't a beneficial critter but a potential pest.

I wouldn't try to irradicate them, by the way. Doing so may result in a bigger problem than you already have. There are plenty of predators out there that will help you keep these down to a managable number. The reason you see so many of them on your zinnia is because that's where they hatched. As soon as they develop wings, they'll disperse. Get rid of the little ones as you find them, though. Brush them off into a bucket of soapy water.