Butterfly larvea

I am pretty new to gardening. My grandfather was the man with all the knowledge but he is tending garden in heaven now.
Please correct me if I get any facts wrong.
I live in the high desert of California.
I have planted peppers, tomatoes, some squash, some pumpkins, and some cantaloupe.
Last year I only had a few peppers and tomatoes. It was pretty successful, especially the habeneros.
Except for the horn worms, and some actual tomato worms. I must have hand picked 5 worms a day for 3 months. the tomato worms showed up late in the season and soapy water got rid of most of them them right before the season ended, but it also seemed to damage the plant, as well as one butter squash plant.
I have learned that the horn worms come from Luna moths, and I believe the tomato worms are from a beetle.
Today while watering, I noticed dozens of what I think are either monarch butterflies, or painted lady butterflies, and a few white butterflies with 2 black dots at the wing tips.
Are these pests that i should be worried about?
What is my course of action?

 

Doubtful. Horn worms are most often from sphinx (hummingbird) moths. Some crops attract moths, especially kohl crops like cabbage, broccoli, cauliflower, etc. Those type of moths are largely white, (at least ours are... others are dark colored... you can Google cabbage moth) and not even half the size of a monarch. They lay tiny eggs on the plants which grow into light green larvae/caterpillars as they grow. My grandfather kept a squirt bottle with baby oil and gave them a shot whenever he saw them. I use BT on anything that might get worms... you can spray plants as often as you like, it won't harm them or any other good bugs. Here's a video I found on horn worms. (Not mine)

If you didn't get a lot of peppers it's probably because you fertilized them. I have learned you NEVER fertilize peppers, you just water the heck out of them. And you can easily over fertilize tomatoes too which burns leaves and stunts growth. Keeping track of your fertilizing schedule is important and more fertilizer is definitely not better. But deep regular watering is. Gramps swore on miracle grow tomato food.

Squash and pumpkins attract squash bugs... the squash bugs will literally take over the garden if you aren't careful. They lay eggs in groups on the underside of the leaves in the corners of the veins. Rip off and put those leaves aside... and let them rot in a bucket of water.

 

We got a lot of peppers last year. I hand picked off all the horn worms. We got an aphid problem on the squash and real tomato worms in the tomato that I used soapy water on but it withered the plant as well as killed the bugs. I will watch the video and google the squash bugs.
Is BT the organic bug spray that "upsets" the worms digestive system causing them to stop feeding?
I think Home Depot sells it as Captain Jacks?

 

Yes, bt is the abbreviation for the Latin name.