Aphids are also pretty easy to control using either Insecticidal Soap or roughly a gallon of water with a tablespoon of liquid laundry detergent added - spray both topside and underside of plants so all aphids get drenched. If you use the laundry soap, wait about 4 hours, then rinse the plant/s with clear water.
This is really pretty environmentally-friendly stuff. The soap replaces an essential component in the bug's exoskeleton - no more exoskeleton. Now the bug-guts leak out. And bug dies.
If you have a really bad aphid problem, repeat the spraying every week or so, just to get all the critters.
PS - Hint: this soap solution spray works on many insects - but not the ones that, like scales, have waxy coverings. The softer the bug-body, the better this works. And it's a contact-killer, not a chemical destroyer.
PPS - Worked just fine on the woolly aphids that threatened my White Pine a few years back! Tree smelled really great, too. Sure got the mailman puzzled!