Inspect, monitor
Check the undersides of the leaves and squeeze the life from the eggs.
IMO, its futile to kill the adults.
One year I outsmarted the bugs by planting the squash really late.
But these bugs are a very hard to solve problem.
Squash bugs by: Doug
I was told not to squish them as the oder attracts more of them. We drown them. Also look both on top and bottom side of the leaf for the eggs and rip that part off and drown them too.
Squash bugs by: Moni
Jeanne
Forgot to mention...You have a huge infestation so start smashing them right away. They do give off a distinct odor when you smash them. If you prefer not to smash, you can drop them in a bucket of soapy water. They are hard to catch as they drop to the ground or hide on the back side of the stems, fruits and leaves(large tweezers may help). Sorry you have this problem...they are a problem for every gardener I know. Just keep after them.
Squash bugs by: Moni
Jeanne
You have squash bugs. These are a problem for all of us that grow squashes of any kind. Being in the MidWest, I find them heading to the garage to overwinter! Since you are in CA here is the website and information from Univ of CA. This tells about the critter and what to do.
Good luck!