They spread by producing crawling young which find new areas to colonise then produce young. In July winged forms fly off to infest other plants. Breeding stops in autumn when immature aphids seek ...
Most plants can tolerate a low to moderate population of aphids without noticeable damage. On some plants, however, large numbers of aphids can distort foliage and flowers and stunt plant growth.
Maintenance: Cut off dead flowers to encourage more blooms, treat common problems like aphids, mildew, and stem rot as needed ... Whether you use this plant in your landscaping as a hedge or specimen ...
Gophers prefer plants. I once put poison down some gopher holes and one of my dogs dug it up and ate it. I had a huge vet bill from that experience. I have another problem with aphids on milkweed.