The cucumber beetle is quite an alarming bug once the larvae hatch and your plants are covered with green beetles eating holes in the leaves. We always encourage the least-toxic methods for protection of your plants, the beneficial insects and yourself. Hand-picking, high-powered hosing-off of plants, insecticidal soaps (or kitchen-sink soapy water) can knock them down for a while. There are chemicals that will kill them (and most other insects including beneficial bees) so they are a last resort. You will find suggestions for all these methods, and a list of chemical treatments, in the links below. A browse through your nursery's insect spray aisle will come up with several commercial preparations - read the cautions and follow the labels.

https://extension.oregonstate.edu/news/fight-bugs-garden-ipm

https://pnwhandbooks.org/insect/hort/nursery/hosts-nursery/rose-rosa-western-spotted-cucumber-beetle...

https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/dahlia-dahlia-western-sp...