Terrestrial Patterns: A guide to why, when, and how to fish them




Terrestrial fly patterns are a subcategory of dry flies used to imitate non-aquatic insects that have either crawled or fallen into the water. These include ants, beetles, crickets, and grasshoppers among others.


In this guide we will cover the following about terrestrial fly patterns:

  • Why Fish terrestrial patterns

  • Best time of year to use them

  • How to fish them

  • Best Patterns to use


Why fish with Terrestrial Patterns?


Give them what they want: Of course trout feeding preferences vary among regions and water types, but according to Mike Lawson's book "Spring Creeks", terrestrials can make up as much as 40% of a trout’s diet during peak months.


While this may be a little less than half of their overall meals, according to a study conducted in 2011 and 2012 by Patrick M. O'Rouke of the Georgia Department of Natural Resources, it represents over 50% of the surface insects they consume. By not fishing terrestrial patterns, you might be missing out on a major portion of dry fly fishing opportunities.


*Click here to see the entire contents of the study by O'Rouke*


Larger Trout: During times of the year when terrestrials are most prevalent, larger fish often have the tendency to hide lower in the water column. The same study by O'Rouke, found that more than 8 out of 10 of the total terrestrials eaten were by trout over 8 inches long. Showing one way to entice larger trout to the surface is by presenting something packed with calories.



Explosive action: Trout feeding on terrestrials have a tendency to attack their prey with considerable force, creating splashy rises that are exhilarating to witness. Check out this video from one of our favorite fishing duos!




When is the Best Time of year to Fish Terrestrial Patterns?


Summer is the best time of year for terrestrial patterns. Seasons can vary greatly among geographic regions, but generally speaking, June, July and August are the best months to fish terrestrials. According to O'Rouke's study, nearly 70% of all terrestrials consumed by a trout in a given year are during these Summer months.



Not only are the vast majority of the terrestrials eaten during the Summer, trout also seem to have a distinct preference for them during that time of year. Of the numerous food options, over 25% of a trout’s diet is made up of terrestrials during the summer months. As the chart below shows, this is distinctly different from the other 3 seasons.



Weather conditions: Windy cloudless Summer afternoons are the best conditions for terrestrials. Since they don’t live or typically spend time in the water, being blown in by the wind is a primary way they get there. Any time you’re walking to a stream and see grasshoppers jumping all around you, it’s time to tie on a terrestrial pattern.




How to Fish Terrestrial Patterns


The majority of time when trout are feeding at the surface on aquatic insects such as mayflies or caddis, they hold in concentrated areas waiting for food to come down a defined current seam or channel. They are somewhat stationary, not moving far to capture their prey, and oftentimes trout will be holding in close proximity to one another.


This all changes when trout are feeding on terrestrials. In the heat of Summer when there are few hatches going on, their meal options become limited. Instead of being able to wait for food to come to them, trout are often required to actively track down their prey. Because of this, they often “cruise” around looking for meals instead of staying in a confined area.



Strategy 1 for fishing terrestrials:


Know where to look

During the hot summer months, trout like to cruise around stream banks that provide shade to cool off and hide in. Many stream banks also have undercuts below surface that large trout hang out in. Look for those shaded stream banks with overhanging vegetation. Terrestrials spend much of their time in vegetation, and if a gust of wind comes along, it’s likely some of them will be blown into the water.


Attractive looking spot for a Terrestrial!

Strategy 2 for fishing terrestrials:


Don't wait for visibly rising fish:

Target attractive looking sections of water instead of waiting to see fishing rising.

Trout don’t feed on terrestrials in a steady fashion like they do on other insects, they tend to “pick them off” one at a time. Therefore, it may be several minutes between rises, and waiting until you see rings on the water before casting could cause you to overlook many opportunities.



Strategy 3 for fishing terrestrials:


Don’t stay in one spot for too long:

Just like the trout cruising around, you too should stay mobile. If you’ve made 4-5 quality casts to likely looking spots with no success, move on. Either no trout are there, or the ones that are aren't interested in coming to the surface to feed. Likewise, if you hook one, don’t let it fool you into thinking there are others in the same area. If you don’t get any interest from more trout after 4-5 more casts, look for other likely spots.



Strategy 4 for fishing terrestrials:


Add movement to your presentation:

While trout are feeding on aquatic insects, they’re often targeting emergers or spinners with limited to zero escaping abilities. On the other hand, terrestrials in the water got there by accident, not by going through the emerging process. This means they’re often alive and active on the water’s surface. Adding a twitch or two while floating your fly close to a trout can entice otherwise disinterested fish.



Strategy 5 for fishing terrestrials


Don't forget about the dry dropper:

It’s a misconception that trout only eat terrestrials on the surface. While most of them are alive and moving on top of the water, a few bugs end up drowning and sinking. If your not having success with a surface floating terrestrial pattern, try using a dry dropper rig (instructions can be found here), with a pattern such as a drowned ant trailing below your terrestrial dry fly.

Hopper Dropper System


Best Terrestrial Patterns


The most universal terrestrial patterns are ants and grasshoppers. These insects can be found in almost every part of the country, and trout of all species will eagerly take them when conditions are right.


Ants (Formicoidea):


Look for ants on the surface right after a hard rain. The downpour of water often washes out their mounds, sending them helplessly into the stream. *Some ants drown after a rain. By snipping off the hackle to create a drowned ant pattern to fish as a dropper, you can target these subsurface feeding trout.*


Triggers for Trout:

Trout seem to key in on the unique impression ants make on the surface. The unique outline of their segments creates a specific silhouette on the surface that trout recognize as food.


Keys to Ant Patterns:

Because trout recognize ants by their distinct body shape, it's essential to tie them with very noticeable segments, leaving space between each "hump". Each stream and time of year hosts different species, so it's best to have a wide variety of sizes between 22-18.



Grasshoppers (Caelifera):

You'll know it's time to fish a hopper pattern when you kick them up out of the grass while walking to the stream. This usually occurs during hot summer afternoons. When you spot them, take your time and examine them for color and size.


Triggers for Trout:

Grasshoppers typically end up in the water by falling from plants or vegetation, causing commotion on the surface. The "plop" grasshoppers make when hitting the water is often enough to grab a trout's attention. Unlike a soft presentation you would make with a mayfly, grasshoppers are usually still alive and active after landing on the water, so adding a small twitch to the fly can trigger a trout to feed.


Keys to Grasshopper Patterns:

Trout seem to notice how low a grasshopper's body sits in the surface, as well as the movement of their legs. Make sure to tie them so the majority of their body sits in the surface instead of on top of it, and use material that creates lifelike movement in the water for the legs.



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Conclusion:


Terrestrial patterns are best used in the hot summer months when they make up over 50% of the insects that trout eat off the surface. They don't create the feeding frenzy that mayflies and caddis often do, but are preferred by larger fish cruising along the stream banks.


Grasshoppers and ants are the most universal terrestrial patterns. When fishing them, make sure to:

  • Fish the attractive water instead of waiting for rises

  • Keep moving if your not having success

  • Add a little motion to your presentation

  • Use a dropper if a dry only presentation isn't producing results


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