First, thank you so much for identifying the red aphids that are infesting my False Sunflower ‘Bleeding Hearts’! I’ve taken your advice and sprayed (all hundred million of them) with insecticidal soap, and hope you’ll indulge a follow-up question: what happens now? The aphids are still all over the plants but they’re no longer moving (HA HA!!) Do I need to rinse them off? Will they just fall off? I ask because I know I’ll have to repeat the treatment in a few days, and it will be easier to see the new culprits if the dead ones are gone. But if rinsing them off will risk reviving them, obviously that’s a non-starter! Many thanks in advance (and I’m sorry if this is a dumb question!) You guys perform such an invaluable service; thank you so much!! And Happy Canada Day!! – Barbara
Insecticidal soap works by suffocating the insects, they disrupt the cellular membranes of the insects, and break down their protective outer coating. The pests become dehydrated and soon die. Once dry the soap will decompose fairly quickly.
It is important to spray the leaves until the soapy solution is just beginning to drip. Don’t forget to coat the undersides of leaves (where aphids tend to congregate). Repeat applications may be necessary every 4- to 7-days (follow the label directions) until the pests are eliminated.
Make sure to apply the insecticidal soap only when the plant has been watered and is well-hydrated since wilted plants are more susceptible to damage.
There is no need to do anything between spraying. The aphids will fall off. It is easy to spot live aphids they will be crawling around on the plant.
The following linkks provide more information on the proper use of insecticidal soap :
June 30, 2022