Terrestrials

By Rick Hafele and Dave Hughes

I spent three days last week on a small stream on the east side of the Cascades in Oregon. I started, as I always do on small water, with a size 14 Olive Beadhead Nymph suspended beneath a size 12 Beetle Bug--a Royal Wulff look-alike. Trout ignored it, as well as the Elk Hair Caddis, and the darker Deer Hair Caddis. I began to think that this stream, which I'd never fished before, was empty of trout.

As I trudged from pool to pool, numbers of grasshoppers scattered from beneath my feet. Something began to sink into my brain. I tied on a size 8 Parachute Hopper, and suddenly that stream was full of feisty fish. Some pounced on it with a splash, but others sipped it so gently that I would notice nothing more than the puzzling absence of the fly.

As an experiment, I tried other dressings, even more traditional grasshopper patterns like the Letort Hopper. Trout would have none of any fly but that Parachute Hopper with its big white wing. That was fine with me; it was so easy to see that it made the fishing easy.

Dave Hughes

From Beneath or Above, Food Is Food

Trout are unbiased feeders. They don't care if their food rises up from the stream bottom to hatch, or if it falls in from above. The fact that trout pay close attention to the surface makes terrestrials an important food source, and one that should not be neglected by anglers. The importance of terrestrials has been shown in numerous food analysis studies. These studies have shown that terrestrials may make up more than 80% of a fish's diet at certain times of the year--especially in late summer and early fall.

Terrestrials are any food that has no aquatic stage. Terrestrial insects of major importance to Western fly anglers are grasshoppers, ants, and termites. Of less importance would be crickets, beetles, leafhoppers (Jassids), caterpillars, inch worms, and the general assortment of terrestrial flies found along streams and lakes.

Hoppers

Grasshoppers are perhaps the best known and most often imitated terrestrial. The West is blessed (or cursed, depending on your perspective) with large populations of a variety of grasshoppers. They can range in size from three-fourths of an inch to over two inches long. The dominant colors are dark yellow or green bodies with grayish brown wings. The wheat fields, open pastures, and grassy banks that are common along so many Western streams, are perfect habitat for grasshoppers.

Hoppers generally hatch from eggs in June and July and are full grown by mid-August. The adults continue to feed until the first frost. The eggs are laid under ground in late September and October. The best hopper fishing occurs in August and early September. They like hot weather, and you will find your best hopper fishing on hot windy afternoons.

Ants and Termites

Ants and termites may appear similar but they are actually in two completely different orders: Ants are Hymenoptera, and termites (sometimes called white ants) are Isoptera. Despite being distant relatives, they have many characteristics in common. Both are social insects living in colonies composed of a queen and hundreds or thousands of workers. Hundreds of different species are known and they range in size from an eighth of an inch to three-fourths of an inch long.

Once a year each colony produces thousands of winged reproductive adults that mate and search for new nesting sites. This is the most important time to fly fishers, since these swarms of flying ants and termites often end up in the surface of lakes or streams.

Trout seem to have a high preference for these hapless creatures, and the fishing can be fast during an ant or termite "fall." The exact time swarms take to the air depends on local species and conditions. Several falls of ants or termites may occur in an area during a season, and you should be on the lookout for them anytime from May through September.

Other Terrestrials

The lesser important terrestrials--beetles, crickets, caterpillars, inch worms, etc.--are only less important because they don't cause selective feeding as consistently as grasshoppers, ants, and termites. When they are abundant and available, though, fish take them greedily and often selectively.

Beetles can be particularly abundant along streams or lakes surrounded by forests, as many of the beetles are major tree pests. July, August, and early September are the best months to find a wide assortment of terrestrials available to fish.

Patterns and Tactics

Banks are the key to successfully fishing terrestrials. Most terrestrials that find their way into the water's surface are concentrated in the foliage along the banks. Banks also provide cover and shade for fish during hot summer afternoons. Thus fish, which move to the banks for cover and shade, are putting themselves in the exact place where terrestrials are most available.

This has obvious fishing implications. On large rivers, terrestrial patterns should be cast as close to the banks as possible. This is more important in streams where banks are slightly undercut and where vegetation hangs out over the water. On small streams, trout often see terrestrials all across the water and will be willing to take an imitation in the middle of the stream.

The shallow water near the shore of lakes may be too warm for fish during midday when terrestrials are most active. Strong winds will at times blow terrestrials far into the middle of a lake or stream, so don't ignore terrestrials when fish are seen rising out from the bank on a windy day. In general, however, terrestrial imitations should be fished tight against the bank wherever the water is deep enough to hold fish. Often a cast six inches from the bank draws a blank, while a cast two inches away brings a quick, violent rise.

Patterns for terrestrials are as varied as the insects they imitate. While fish sometimes feed selectively on terrestrials, they generally find them a quick easy meal and are ready to take whatever falls in. Complicated, exact imitations are rarely necessary, but patterns should be selected with the proper size and silhouette in mind.

Rick Hafele is a professional entomologist and fly fishing writer living in Gresham, Oregon. His most recent book is Nymph Fishing Rivers and Streams. Rick's good friend Dave Hughes is fly fishing's most prolific author, with over 30 books to his credit including Trout Flies. Together they are the authors of Western Mayfly Hatches.