Parks' Fly Shop: Guide to Yellowstone Area Terrestrial Insects, Yellowstone Hatch Chart

Guide to Terrestrial Insects in the Yellowstone Area

Fishing terrestrial insect imitations is a huge draw for many visitors from midsummer through early fall. The table below includes information on the most important terrestrials you should expect to match, flies to match them, and so on. Please note that instead of emergence or activity time, I discuss habitat, since each type of terrestrial is more likely to be found in certain places, and all terrestrials are more active from late morning through late afternoon.

Note also that much of the following discussion refers to pattern colors rather than to specific insects. There's a great deal of overlap between terrestrials and attractor dries, and many terrestrial patterns may have realistic outlines but attractor-type coloration.

Terrestrial Insects Emergence Table

Table Key: X=primary importance, x=secondary importance, blank=unimportant
Name Description Habitat Month
      Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Grasshoppers, Standard Creamy yellow to golden brown, darker above. #6-16 Primarily areas with grass or sagebrush below 7000 feet, but possible even in mixed woodland/meadow areas.             x X X x    
Grasshoppers, Oddballs Various colors and sizes from bright yellow to peach to chartreuse. #6-14 Most important at lower elevations such as near Gardiner, where HUGE numbers of grasshoppers are around.               X X x    
Grasshoppers, "Attractor" Same size range, but pink, purple, bright green, etc. Same as oddballs, but colors are often exaggerated or nonrealistic: bright pink or flaming yellow, for example.               X X x    
Crickets and Cicadas, Small Black, #8-12; patterns often have a sparkly belly. Most useful in the Lamar drainage, the Black Canyon of the Yellowstone, and outside the Park on the Yellowstone.             x x X x    
Mormon Crickets Huge, prehistoric, almost "greasy" gray-black. #4-8 Most common in the Lamar drainage and on the Gardner.             x X x      
Ants #14-20. Black, cinnamon, and bicolor can all be important. Possible everywhere. Especially important on the spring creeks and in the Lamar drainage.       x x x x X X x    
Flying Ants Usually black or bicolor, most common in late summer. #14-16. Most important on Slough Creek.             x X X x    
Beetles Black or slightly iridescent most common, but brown and olive also possible. #12-18. Most important in the Lamar drainage. Also a good bet on Firehole tributaries in late summer.       x x x x X X x    
Beetle, Longhorn Distinguished by its bark-like color and long antennae. #10-12 2xl. Most common in areas with at least some evergreen trees.             x X x      
Spruce Moth Ginger to mottled tan, #12-14. Critically important in heavily-wooded areas, but can bring fish up as long as there are at least scattered evergreens.             X X x      
Bees #12-14. Looks like any other bee... Most important in the Lamar drainage.           x X x x      

Discussion of Insects

Boldface type indicates fly patterns. Italics are used for scientific names.

Grasshoppers, Standard

Grasshopper season starts mid-July in dry years and late July in wet years. It can run until early October at lower elevations provided we don't get below freezing daytime temperatures for more than a couple days running. Hoppers are important everywhere, even in wooded areas provided the streambanks are grassy, but they're most important on meadow streams in the Lamar drainage and on the Yellowstone. Hopper fishing is best on windy afternoons in mid-late August with some cloud cover, but fish will come to them at any time, even in the morning.

Our "default" grasshoppers range from cream-colored to golden yellow underneath and are typically dark tan to light brown above. Rear legs are either red or black-barred golden brown. About half of your hoppers should follow this template. Rainy's Grand Hoppers look "right," and usually fish right too. Other good choices are Chubby Chernobyls, GFAs, Letort Hoppers, and Chernobyl Hoppers. Turck's Tarantulas and Yellow Stimulators are more multi-role flies, but they work for hoppers too, especially on smaller streams. Sizes should be heavy in the #8-12 range, but having a few up to size-6 and some tiny Grand Hoppers is also a good bet. Every year there's a few days when they want the great big ones or the tiny ones and nothing else. Fish are particularly likely to prefer small or very large hoppers when they've been heavily pressured. Oddball and "attractor" hoppers also work better for heavily-pressured fish.

Grasshoppers, Oddball

During wet years, especially at low elevation where there are TONS of hoppers, some natural hoppers take on unusual colorations. Most common are dark brown, light olive, pale peach, golden yellow all over, and even faintly pink. Having a few of the patterns mentioned above in some of these colors is a good idea, especially since most anglers stick to the standard tan-gray-creamy yellow color range and the fish see a lower percentage of "fake food" in these oddball colors. Chernobyl Ants, Chubby Chernobyls, and GFAs are great to experiment with in oddball colors, mostly because they're easy to whip out in a hurry if you tie and durable so you don't have to tie (or buy) many.

Grasshoppers, "Attractor"

Lately, hopper patterns that retain hopper silhouettes and sizes but push the "oddball" colors to new extremes have proven extremely successful. Pink hoppers such as the Pink Pookie, Western Lady, and Pink Chubby Chernobyl have proven particularly effective. All three patterns take the faint pink cast of some natural hoppers and push it to "baby pink" or even neon pink and fuchsia tones. Bright yellow and chartreuse are also good choices. Neon orange also worked for some of our customers last season. Besides the patterns already mentioned in this entry, the others given above tied in the appropriate sizes are good choices, especially little green Letort Hoppers.

Crickets and Cicadas, Small

Small black hopper/cricket/cicadas are not usually as important as hoppers on big rivers, but they can really fool heavily-pressured fish at times. Cards Cicadas and black Swisher's Foam PMXs are our go-to flies in this category, but black and purple Chubby Chernobyls are also good bets. In 2008 the Card's Cicada was our best September terrestrial, while Ben Jewell and Mike Leach had good success with the black PMX in 2010.

Mormon Cricket

These horrifying bugs are best imitated by a Fat Albert. The problem with them is that they are so big the fish often can't get them in their mouths, especially on the Gardner where they are particularly common.


Wingless ants are usually a changeup fly or dropper rather than a main fly, but they can sometimes be just the ticket, especially when the fish have seen far too many hoppers. Carry black, cinnamon, and Ben's Bicolor Ants in #16-20. A few sinking bicolor ants are also a good idea, especially if you're floating. Ants don't float well, so fishing one 4-6" under the surface is a great bet.

Flying Ants

Slough Creek and to a lesser extent other meadow streams occasionally see heavy falls of black or bicolor flying ants in late summer and early fall. The fish can get really excited when this happens, so even if it is an unusual event, you need to carry some ants with Zelon or CDC wings to match flying ants, in sizes 14-16.


Besides ants, beetles are our other go-to "hopper trailer." Fish one behind a hopper and a trout that refuses the big fly will often take the inconsequential little beetle drifting along behind it. The PFS Beetle in basic black is the standard bet, but various other colors (especially prismatic finishes or those with flashy underbodies) are also good choices. All should be #12-18, with heavy emphasis on smaller sizes.

Longhorn Beetle

Longhorn beetles are much less common than the smaller beetles, but they're fun to imitate because they're so big. Tie a wood-grain or black foam beetle with long hair or flash antennae.

Spruce Moth

Spruce moths are SUPER important in mid-late summer on streams that have evergreens, even just a few of them. Walter had a great day with clients fishing Spruce Moths floating right through Livingston a couple seasons ago, just because of the ornamental evergreens in town, for example. On streams like the Gallatin and upper Soda Butte Creek, the fish can get quite selective to the heavy "spinner-like" falls of this insect. Carry three versions, a high-floater such as the MFC Para Spruce Moth, a lower floater such as Wiese's Widow Moth, and a film-floater/sinker like Korn's Spent Spruce Moth.


Bees are a relatively new changeup fly for fish that have seen one (or a hundred) too many hoppers. We sell the CDC Bee, but there are various foam-bodied versions on the market that will work, too. These have been good bugs in the Lamar drainage over the past couple seasons.

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