Adhesive Eyes for Fly Tying – Nicholas’ Guide to Matching Hook and Eyes Sizes

Eyes for fly tying. Big eyes. little eyes. All colors you can imagine. Here is your single source of how to select the proper eye based on hook and fly size.

Welcome to the World of Adhesive Eyes for Fly Tying
This blog post is created to serve as a guide for fly tyers who need recommendations for matching the size of adhesive eyes to hooks, deciding what length of fly might look right with different eye sizes, and pairing Fish Skull Fish Masks with hook and eye sizes. I’ll also provide tables to convert inches to mm and mm to inches.

The fly shops and catalogs are stuffed to overflowing with adhesive eyes. We have size options, color options, pupil options, and the combination of choices that are so complex that it can be difficult to make decisions. What size eye will fit on corresponding hook size. Do I want a round pupil? What about a horizontal pupil? Should I try the asymmetric elongated horizontal pupil eyes? Are yellow eyes better than red or silver or pearl?

Are there too many choices in adhesive eyes?
Of course not. We are, after all, creative artists when we sit at the fly tying bench, and the availability of different sizes, colors, and shapes of eyes only provides us with a wider range of options for how we may adorn our flies, and it also allows us more choices when it comes to imitating specific baitfish, on the presumption that our target fish species are feeding selectively.

Here’s what you will find in the remainder of this post.
1. Inches to mm Conversion
2. mm to Inches Conversion
3. Recommendations for Hook size – Fly Length & Eye Size in Inches
4. Recommendations for Hook size – Fly Length & Eye Size in mm
5. General considerations regarding adhesive eyes for fly tying
• Does the glue, epoxy, or UV cure matter?
• Saltwater vs. freshwater hooks
• Are labeled sizes accurate?
• Are the adhesives sufficient to secure the eyes on a fly?
• Is pupil shape crucial to fly effectiveness?
• Does eye color make a difference to fly effectiveness?
• Can Fish-Skull Fish-Masks be used with different eyes?

First, Let’s run through the metrics of converting inches to mm, and metric to English measurements, in the following two tables.

Inches to mm Conversion

Now, let’s review my recommendations for deciding what size eyes are best for different hook sizes.

Recommendations for Hook size &
Fly Length & Eye Size in Inches

General considerations regarding adhesive eyes for fly tying.
There is more to the process of tying flies with adhesive eyes that merely getting sizes matched. Here are some of the questions most tyers ask about using these eyes.

Does the glue, epoxy, or UV cure matter?
Yes. This is a crucial factor, and the best advice I can offer is that the smaller eyes require a thinner consistency of UV cure and the application of less cure to the fly. Application of Fish-Skull Fish Masks generally requires some sort of superglue, like Zap or Lock Tite. I tie more with eyes secured to my streamer with a big head formed of UV cure, usually Solarez. These UV resins can be made thinker by placing the bottle in a bowl of warm water and being careful that the bottle does not tip over in the bowl.

Saltwater vs. freshwater hooks
The hook-size recommendations I have made here are based entirely on saltwater hooks, or on the largest of freshwater hooks that might be used on a giant pike, alligator, and musky flies.

Are labeled sizes accurate?
This is a quality control issue. My opinion in this regard is that, yes, the sizes are accurate within a batch of eyes produced in a specific product run. These might be a hundred thousand cards with a dozen eyes on each card, and I doubt that the size varies at all within this product run. As with most products of low value and big number, the size of eyes from one production run to another might vary. On the whole, however, the advertised size is probably pretty darn accurately labeled.

Are the adhesives sufficient to secure the eyes on a fly?
No. The adhesives on the back of these fly tying eyes are adequate to hold them on a paper backing, but they might slip off a plastic sheet. I find the adhesive is usually OK to lightly hold the eye in place while I add some other glue or UV cure to make a more permanent bond on the head of the fly.

Is pupil shape crucial to fly effectiveness?
Honestly, I do not know. I usually fish the round-pupil eyes, but will tie with any eyes I have handy on my fly bench. I do not like to tie a set of a dozen flies with three different styles or sizes of eyes, but that is my OCD squeaking-out, rather than knowledge of how the fish will react. My advice here is to consider your intuition as well as whether or not you are trying to imitate a particular baitfish when making this choice.

Does eye color make a difference to fly effectiveness?
My opinion is that eye-color is more important to the angler than to the tyer, but some of my friends claim that some eye-colors induce more strikes than others. I leave this one in your hands to decide. Yellow eyes are common on some baitfish, and red colors could imply an injured prey. The palate of colors we have at hand in the fly shops is worth taking advantage of in you have any interest whatsoever.

Fish-Skull Fish-Mask Size V. Hook Size V. Eye Size

Can Fish-Skull Fish-Masks be used with different eyes?
Sure, but finding a good match is tricky, so unless you have several packs of eyes laying around that you can experiment with, I recommend ordering the Fish-Skull Living Eyes so there is no chance of getting an imperfect fit.
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My Best Wishes to all, and my hopes that the information in this post is useful.

Jay Nicholas, June 2020