All About Fly Fishing!

Japanese Beetle Fly

Looking for something that will bring the worst out in trout? There's a silver lining to the cloud of Japanese Beetle infestations in some parts of the country. Grab a cup of coffee and learn to create a great imitation - By John Guldin.

japanese beetle fly

It was very early on a June morning when I carefully eased into a familiar limestone stream armed with a special fly that I was given by a special angler. Ray Deibert began fly fishing in the early 20th century when almost all fly fishing was with 3-5 wet flies being cast "across and down." He built several rods for me, taught me much about fly tying and showed me quite a few effective patterns. One of the best patterns he ever taught me was now knotted to my leader as I stripped out some line making ready to cast.

I had waded this stretch of stream many times since the opening day of trout season and each time the fish became harder to fool. Now, in late June, the water was warmer and the trout seemed much more lethargic and selective. Nonetheless, I was about to cast Ray's creation and I was buoyed with anticipation. I false casted two or three times before directing the fly to a spot a little upstream from an overhanging bush. The current caught the fly and it drifted to a shaded spot. I saw its eye.

I remember just the eye of the trout as it came up from the depths and raced towards the fly. The eye was filled with a fury that I hadn't seen before in a small-stream trout. Could it be this pattern triggered such an aggressive response? I landed the 15" brown trout, removed the fly and sent him on his way. Many times since that day, I have seen trout, for whatever reason, react with reckless abandon when this special fly is on their home turf. The special fly is a unique and innovative imitation of the Japanese Beetle. There are many patterns for the Japanese Beetle, but I believe my now deceased friend, Ray Deibert, hit on the best.

The Japanese Beetle [Class: Insecta; Order: Coleoptera; Family: Scarabaeidae; Genus: Popilla; Species: japonica] is native to Japan and was first identified in southern New Jersey around 1916. One theory is that the beetles were unwanted stowaways on a ship carrying agricultural products that originated in the Far East. The beetle soon spread throughout the eastern United States and, today, its range is growing larger as it expands within the U.S. and Canada, being first discovered in Yarmouth, Nova Scotia, in 1939. While it eats as many as 300 different species of plants, flowers and vegetables, it also is eaten with great gusto by trout. For fly fishers, the Japanese Beetle infestation is an example of "Every Cloud Has a Silver Lining."

Fly tiers have concocted many patterns to imitate the Japanese Beetle. Some employ deer or elk hair or various synthetics. One tier I know uses just a small piece of black Styrofoam cemented to a hook based upon his belief that the basic oval silhouette the trout sees from beneath is the most important factor. I have tried three or four different Japanese Beetle patterns but once I learned about Ray's method of tying the beetle, I felt it was the best.

The real key to the pattern is the use of a coffee bean. This is because a coffee bean is not only the approximate size and shape of a Japanese Beetle, but it also makes a realistic "plop" sound when landing on the water, just as the natural does. I believe this is a definite "trigger" to a trout's natural predatory instincts. The coffee bean version of the Japanese Beetle is relatively simply to tie, but it does take time due to the numerous steps and the drying periods between them. That is why I suggest tying five or six at a time so that while some are in a drying or curing stage you can be preparing the others.

Materials For The Japanese Beetle Fly:

Coffee Beans:

Will any coffee bean that approximates the size of the Japanese Beetle work? No. Believe it or not, the lighter-colored Mocha/Java bean is a much better bean than the darker-colored Expresso, Tico or Viennese Roast. This is because the more a bean is roasted the more brittle it becomes. A rule of thumb is that the lighter the color of the bean, the less roasting it has undergone and the better it will work for this pattern. From your pile of light-colored coffee beans, select ones of appropriate size and that have a centered and fairly straight groove or fissure in the bottom of the bean.


The selection of a hook is related to the size of the bean, which is related to the size of the natural beetle. I use light wire hooks that were designed for dry flies. Two hooks that have worked well for me are the Tiemco 100 or the Mustad 94940. Hooks in sizes #12 to #14 are generally the sizes that will fit a coffee bean.


You can use black 3/0, 6/0 or just about any size black thread you have on your bobbin. The only purpose of the thread in this pattern is to provide a stable platform for the cementing of the bean.

Legs: Peacock Herl


Testor's Copper Gloss Enamel Paint and Model Master British Green Metallic Paint. You can substitute any quality hobby paint. You will also need a small watercolor-type paintbrush.


Zap Gel, Epoxy or any other similar glue. I prefer Zap Gel because it is thick enough to stay in place and sets up within seconds.


Japanese Beetle Fly Tying Instructions:

Step 1: Select a coffee bean according to the criteria set forth above keeping in mind that the male species is approximately 1/2" long [10mm] and 1/4" wide [6mm]. The females are slightly larger.

Step 2: With a small file, pocket knife or your fingernail, clean out and enlarge the groove in the bottom of the coffee bean to make it as straight and as smooth as possible.

Step 3: Select a dry fly hook to fit the coffee bean. The eye of the hook should extend past the front end of the bean and the bend of the hook should extend past the rear. In other words, the bean should set only on the shank portion of the hook.

Step 4: Place the hook into your vise and wrap the shank with black thread so that it will fit into the groove. This may take several attempts of wrapping and placing the bean into position and then adding another layer of thread. When the groove fits snugly onto the hook, you have the proper fit.

Step 5: Place a small amount of Zap Gel into the groove of the coffee bean and set it onto the prepared hook. Hold it securely until the glue sets. Then place it on a drying wheel or, as I use, a block of Styrofoam until the Zap Gel thoroughly cures. While you are waiting you can repeat Steps 1 to 5 on several other beans. When all coffee beans are firmly cemented, go onto the next step.painting the fishing fly

Step 6: Grip the bend of the hook with a forceps and paint the "back" of the coffee bean with the Testor's Copper Gloss Enamel paint and set aside to dry. Repeat with each bean.

Step 7: Next, paint the bottom of the bean, including the hook shank and thread, with Model Master British Green Metallic paint and let it dry. The natural insect is described by most entomologists as having a metallic green abdomen. However, if you cannot find a metallic green paint, don't worry. I used Testor's Black Flat Enamel Paint for years with great fishing success.

Step 8: You are now ready to affix the legs. Japanese Beetles have six legs and many patterns call for the placement of all of them. Although I am by no means an entomologist, I have conducted a layman's study of the Japanese Beetle's actions while in the water. I have placed some "specimens" in our swimming pool where I observed them from underwater. My observations were that upon hitting the water the Japanese Beetle tucks in the four forward legs, but keeps the rear two extended to act, I believe, as rudders. Thus, the two rear trailing legs are an important part of the silhouette.

Fishing tests using flies with six legs and with two legs support my belief that only the rear pair of legs, which are longer and somewhat thicker than the other four, are the only ones necessary for the pattern. Using two legs makes tying easier too
All that being said, take two pieces of peacock herl and cut them one inch long. .japanese beetle painted dotThey will be trimmed later but for now the longer sections are easier to work with. The legs should be glued on the bottom of the bean on each side of the hook shank in a trailing "V" shape. If you are able to find a natural beetle, duplicate the angle of the rear legs. Otherwise, the angle between the legs should be between 40 and 45 degrees. When the glue is dry, trim the legs to approximately 5/16" to 3/8".

Step 9: Options a. The most popular option is to place a small dot of fluorescent orange, chartreuse or hot pink paint on the back of the fly to increase visibility.

9b. Some tiers paint small white dots around the bottom edge of the bean along with black "wing" lines to duplicate more closely the markings on a natural Japanese Beetle, which has white tufts along sides and rear of the abdomen. This may have some benefit but I have never taken the time to add this extra step.

japanese beetle fishing fly When the Japanese Beetles appear in your area this summer, head to the stream with your newly created imitations. By the time you fish the Japanese Beetle, usually June is the earliest they appear in any numbers, you should be familiar with the haunts of the remaining trout.

Go to those spots that have bushes and trees close to the stream. I have most of my success fishing around and under trees and bushes that overhang the stream. Many Japanese Beetles, which spent the night on the foliage, try to move about or fly off before the sun has warmed them. As a result, some fall into the stream. The best time to fish this fly is early in the morning while it is still cool since Japanese Beetles normally do not begin flying until the temperature reaches close to 70 degrees Fahrenheit (~21C).

Use a tippet that is stiff enough to turn over the fly but not so stiff that the fly acts as if it is on the end of a stick. Depending on the weight of your fly a 3x to 5x tippet will work well. Fish upstream. The cast should be slow and deliberate with a big enough loop to allow the fly to "plop" into the water several feet above the suspected lie. Quickly remove any slack from your line and wait for the hit. Trout sip Mayflies, Japanese Beetles they attack with pugnacious aggression!

I have found that the majority of strikes come within seconds of the "plop." If there is no response, try several more casts and then move on to the next spot. If a fish is where you think, it will hit the fly within three or four casts. Remember, the best time to fish the Japanese Beetle is in the coolness of the early morning so you only have an hour or two. Therefore, keep casting and moving.

A few slashing attacks by trout will convince you that the Japanese Beetle fly is a fly that is "Good to the Last Plop."