small longer living insects besides spiders

I heard termites can live for a very long time. At least their queen that is.
The problem with insects is, most of them do not live very long. Typically one life cycle of most insects are within one year. What you need isn't an extremely long lived insect species, you should be looking at how to sustain your colony. Getting a queen ant might be a start in my opinion lol.

By the way, spiders aren't exactly insects.