Some of the more overlooked terrestrial imitations are ant patterns. In the mid to late Summer and early Fall many anglers immediately go directly to hopper fishing, which of course is fun and effective, but isn't the only terrestrial action to be had. Here are a few tips to fishing ants effectively:
Fish ants any time, but especially in the middle of the day. Terrestrial insects are much less active when it's cool so they are more likely to make a mistake and find their way into the water when tons of them are scurrying around in the heat of the day.
Use ants as searching patterns. Fish them blindly to likely looking spots. Don't worry if fish aren't rising, there usually aren't enough ants to cause fish to rise regularly. If the fish have been eating ants they will know what they are when they see yours.
Fish ants in forested areas as well as meadow sections of streams and rivers. Unlike hoppers that only live in grassy areas, ants live everywhere and so even in forested sections of streams there will be ants.
Fish ant patterns near the banks. Even more so than hoppers, it is pretty unlikely that ants will drift far from the banks. Some opportunistic fish mid stream will eat them but the likely spots near stream-side vegetation and undercut banks will produce more fish on ant patterns. Small streams with a lot of overhanging vegetation are the exception; in these streams ants could be almost anywhere throughout the stream.
It is often effective to fish two ant patterns at once. Many times it's best to tie on a visible pattern like a parachute ant, Chernobyl Ant, CDC ant, or something similar and then trail it with a smaller less visible ant pattern like a fur ant, a small foam ant, or even a hard body ant. Don't worry even if the smaller ant pattern sinks. Simply watch the more visible pattern for strikes.
I've heard it said that fish that start to key on ants actually develop something like an addiction to them. I don't know if that's entirely true but a few years ago I had an eye opening experience on a guide trip where a somewhat slow day turned into a 50-fish day for my client once we found that ants were the preferred choice on the menu. It was awesome!
Get out there, ant patterns tied on, and hopefully I'll see you on the water.