Rini,
Could you describe them a little more? Are they winged or wingless? Do they jump when disturbed? Are they on the underside of the leaves or on the flowers? How big are they (etc.)? The first link below has some excellent images (unfortunately, no close ups of aphids) and the second link is from Cornell and is well worth the read. Hope this helps.

Colin

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7466.html#COMMON%20INSECT
http://www.hort.cornell.edu/gardening/fctsheet/egfactsh/roseipm.html

Colin-

Thank you for your reply. I think they are aphids. I've been looking at other information on this website and the descriptions fit. They are actually more light green than yellow (maybe the light was playing tricks on my eyes). I've been knocking them off with water and hopefully that will do the trick, although I'm keeping an eye on them.

Oddly enough they are only found on one plant so far.

-Rini

Rini,
One way to be sure if they're aphids is to get a magnifying glass and look at the back of the aphid. If, on either side of the end of the abdomen you see a pointy structure (called a cornicle, "exhaust pipe," or "tail pipe"), then you can be sure they're aphids.

Regards,
Colin

Colin-

I'll check when I get home. If they don't have the pointy thing at the back, what might I be looking at?

thanks
Rini

I have some yellow bugs with balck legs on my oleander. Do you have any idea what they are? I did knock them off with water, but the tree is about to bloom and I hate to spray it right now. HELP!