Q: Please tell me if these yellow insects are harmless. They are multiplying fast but only on these flowers.
A: They aren’t harmless but in the grand scheme of things, they aren’t terrible either. Aphids as a family will suck sap from your plants and reduce their vigor. The good news is they are tiny and each one does very little damage. This species are sometimes called oleander aphids (Aphis nerii) and they prefer certain types of plants such as milkweed and oleander. A simple spray with your hose once in a while will keep the population down enough to protect your plants.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed to tucsongardensage@gmail.com