The smaller cats are hard to see, that's for sure. I spray Bt for most. I understand that it doesn't take out the larger ones very well, but it has helped a lot with small to mediums. I was having a time with climbing cutworms(medium sized, about 1 1/2")on many of my plants and it took care of the ones I couldn't find. It also takes out cabbage loopers which were decimating my tom plants last year. HTH

Bt, sold as Dipel dust or Thuricide liquid spray, is the standard common treatment for all forms of caterpillars/worm pests. Lots of information here about it.

Dave

Since you are jn my zone I wanted to note that I did find one fruitworm this season, and it was the first time I had ever seen one. I thought those were strictly southern pests! I am starting to see a variety of insects that I have never before encountered. It perplexes me.

Bonide's 3-in-1 is supposed to be good for fruitworms, and since I sprayed last week, the count has plummeted, although I did pick 3 or 4 off this morning. I also found, on the underside of a leaf, about a dozen tiny eggs laid out in a diamond shaped pattern.

They went down the garbage disposal.

I had fruit worms on the fruit that laid on the ground, on the part that touched the ground. I'll try better cages next year.

I have read that horn worms glow under a blacklight at night. I might buy a cheap handheld blacklight next year and try that trick.