Hungry caterpillars and other uninvited dinner guests

The very hungry caterpillar
The culprit, captured. Before I finally discovered him (not easy because of his camouflage) this Very Hungry Caterpillar had enjoyed at least a week of meals. The evidence (circumstantial, I admit): a swiss cheese pattern in my prize 'Cherries Jubliee' nasturtiums' flowers and foliage. It was catch and release, though, as after the photo session I tossed him into the shrubs below my balcony.

In the comments on the previous post, Tess asked a very good question:
Do you know a good website for identifying caterpillars?
Short answer: a week ago, no. But this evening, thanks to Tess's query, which motivated me to do some research, I know a bit more about how to identify caterpillars and other insects, as well as encourage the good critters to take up residence and control the bad bugs organically.

Here are the resources I've added to my virtual gardening bookshelf:
Based on mug shots, I think the caterpillar in the photo is a very plump cabbage looper.

There are still a lot of gaps on organic pest control in my library so please feel free to contribute your favourite resources in the comments section.