If you think terrestrial imitations are only for summer fishing, you’re missing a great deal of dry-fly action. The normal thought is that trout ignore land-bred insects in the spring and early summer, until mayfly and caddisfly hatches dwindle with the heat of summer. They ignore terrestrials about as much as you ignore chocolate mousse when out to dinner.
Stomach content studies of trout show that land-bred insects are dominant trout food not only in August, but also in May, June, and September. Well into October and November, beetles can be the most abundant food in a trout’s stomach, and leafhoppers have been seen there as late as December. The studies I referred to above were done in upstate New York, and if you’ve ever spent December in Rochester or Syracuse (I’ve done both), it’s hardly what most fishermen would consider terrestrial weather.
I’ve known about these studies since my college days, but do you think I’ll be smart enough to act on it? The other day, fishing a wild trout river in late morning, I noticed a number of big March Brown and Gray Fox mayflies on the water, plus a smattering off caddis in the air. There were no rises. Feeling very clever, I put on a big Hare’s Ear Nymph to imitate the mayflies and a Lafontaine Deep Pupa in case the fish were eating caddis. It’s a shallow, clear stream, so I added a pea-sized glob of bright red Strike Putty instead of my usual yarn indicator the size of a baby sparrow. Three fish rose to the Strike Putty before I was smart enough to switch to a beetle. Nobody touched the nymphs. Now if I had been in a river with hatchery fish I would have told you they took the indicator because it looks like a food pellet, but no fish have been stocked in this river for 20 years. I can’t imagine those trout mistook my round red indicator for anything but a beetle.
Do trout prefer terrestrials to aquatic insects? It’s said that trout like the taste of ants, but I’m leery of anyone who claims to know about the taste preferences of the American public or Labrador retrievers, much less silly little fish. However, it has been proven that adult trout are good at judging the relative caloric value of prey and balancing their energy expenditures with energy inputs. A size 14 beetle would seem to have a lot more “meat” than a size 14 mayfly, and a big grasshopper must provide more calories than anything except a big minnow or crayfish.
If you fish small streams, terrestrials are even more important than in larger rivers. A trout’s diet in some small streams is made up almost entirely of terrestrials, as these smaller waters don’t have large expanses of insect-producing riffles. This may be why such so-called “attractor” flies like Humpys and Royal Wulffs are so effective in small streams—both flies, from a trout’s-eye view underneath, look suspiciously like beetles or other land-bred insects. And an Elk-Hair Caddis looks very much like a tiny early-season grasshopper. But, you say, these flies have wings. So do beetles, bugs, katydids, and many ants!
Unlike fish responding to a hatch, trout can be eating terrestrials and you’ll never notice. One reason is that they might see a beetle only once or twice an hour, and the chances of you looking at exactly the right spot aren’t good. An even more important reason is that when trout eat low-floating terrestrial insects, there is hardly ever a splash. Sometimes you see a subtle ring on the water, sometimes a black snout poking above the surface, and sometimes you see a hopper just disappear into a hole in the water with no visible sign of a rise. Best places to try a terrestrial fly are where riffles deepen into a dark slot (especially near a deep bank but not necessarily), in concave impressions along a bank that form small bays, and along undercut banks, especially ones that flow through meadows.
Finally, one of the most deadly midsummer rigs I’ve ever used is a tiny nymph tied as a dropper to the bend of the hook of a beetle or hopper. Tie a size 14 beetle or ant to a 12-foot 5X leader. Knot an eight-inch piece of 6X Mirage tippet to the bend of the hook of the beetle with a clinch knot, then tie a size 18 Pheasant Tail Nymph to the end of the 6X tippet. You’ll catch about half of your fish on the beetle, and on the other 50% you hook on the nymph, the beetle makes a damn good but subtle strike indicator.
Tips for Fishing Terrestrials
Best Terrestrial Flies
You don’t need a broad selection of terrestrials. Fish are seldom selective to a certain kind of beetle or ant. I would, however, carry a broad range in sizes, as the trout seem to prefer smaller or larger flies on a given day or in a certain river. I have no idea how to predict what size they might like. If the water is high or fast, lean to the bigger sizes to get their attention, and if it’s low and clear, pick a smaller pattern to avoid spooking them. Other than those guidelines, you’re on your own.