Butterfly FAQ: How to Tag A Monarch Butterfly in Six Easy Steps

One of the most common questions we get at the Texas Butterfly Ranch is how the heck do you tag a Monarch butterfly?

Ready to tag some butterflies?

Ready to tag some butterflies?

It’s pretty straightforward, really.  You’ll need a butterfly net, a clipboard or mini notebook and a writing utensil to record your findings.   You’ll also need tags issued by Monarch Watch ($15 for 25 tags).    I recommend a hat and camera, too.

Before you go, apply sunscreen or insect spray if you use them, then wash your hands thoroughly.   Monarchs and other butterflies are more resilient than we think, however, Deet, Paba  and other chemical contact with their scales, wings and bodies should be avoided.  There’s no need to sterilize your hands or wear gloves.  Just wash your hands.

Monarch Watch tags and data sheets

You’ll need Monarch Watch tags and data sheets to tag Monarch butterflies. And a butterfly net.

When should you go tagging?  I like late mornings after my second cup of coffee.   By then, the butterflies have had a chance to warm up their bodies and are out flying and nectaring.  Remember, butterflies won’t fly if the temperature is less than 60 degrees, so late mornings and afternoons on sunny days are ideal.   Right before sunset is good, too, especially when they’re migrating.  In the Hill Country in October, masses of Monarch butterflies will often drop from the sky around dusk and look for roosting spots—usually in protected tree limbs and often near water sources.

Ready for some tagging?  Here’s how to do it.

  1. Locate butterfly

Millions of migrating Monarch butterflies will pass through the “Texas funnel” on their way to their ancestral roosts in Michoacan, Mexico, over the coming weeks and months.    According to Monarch Watch, peak migration for San Antonio and Austin will be October 2 – 22.

Frostweed is a fall favorite nectar source for Monarch butterflies.

Frostweed is a fall favorite nectar source for Monarch butterflies.

Typically, we see a first pulse of vanguard Monarchs around Labor Day in the Hill Country and in our San Antonio and Austin gardens.  In September we’ll consistently see individual Monarchs trickling through town.  By October, groups will show up and form evening roosts in trees and large bushes like Poverty Weed along our rivers and other protected locations.

The best places to see them are along our streams and rivers where late season blooms offer a nectar rich rest stop.  Monarchs fuel up on their journey south, so anywhere with late season butterfly-friendly flowers—native and Tropical milkweeds, Gregg’s Purple mistflower, Cowpen daisies, Frostweed, Goldenrod, lantana, for example—should draw them, as well as other butterflies.

Your own garden, if it has butterfly-friendly flowers blooming, should draw Monarch butterflies.  Look, observe, wait.   And be patient.  For some prime Monarch butterfly spotting, stop by the Milkweed Patch along the Museum Reach of the San Antonio River this fall.

2.  Net butterfly

Netting a Monarch butterfly—or any butterfly for that matter—is more challenging than it looks. The flitting creatures exhibit extreme skittishness and their compound eyes afford them a 360-degree field of vision. The slightest movement can send them sailing.

When I first started tagging Monarchs, I diligently chased them in flight. After slipping in the river more than once and skinning my knee after tripping down the steps at my house while in hot pursuit, I resolved to only try and net Monarchs when they’re roosting or nectaring. I’ve witnessed several ace netters with excellent hand-eye coordination, quick reflexes, and a sniper’s aim nab butterflies in flight, but I’m not among them.

Monarch nectaring on swamp milkweed

It’s easier to net Monarch butterflies when they’re nectaring. Sneak up on them from behind.

Suggestions:  wear low-key clothing that blends into the environment, move slowly, keep quiet and sneak up on them from behind.  Once you swing your net, the butterflies will scatter.  It resembles fishing in that sense;  when you cast your line, the fish get spooked and flee, but they’ll be back. After a few minutes, the butterflies will resume their activities—nectaring, resting or roosting.  Or they may fly out of your reach.

Once you get a butterfly in your net, be sure to flip the net sock over the circle of the rim—otherwise the clever insects can slip out.   With the net sock folded over the net structure, they will remain in your net.

Annie Schenzel demonstrates proper net technique

Annie Schenzel demonstrates proper net technique. See how the net sock is draped over the rim? No butterflies can escape.

Some folks take the net down to the ground after they swoop the butterfly into the net to ensure the butterfly doesn’t escape.   This is especially helpful when you capture many at once.

3. Collect butterfly/butterflies from net

Once the butterfly or butterflies are in the net, gently reach in and clasp an individual in your cupped hand, wings folded together if possible.  (No insecticides or sunscreen on your hands, please.)  The butterflies will flail around in the net, so try to calm them by folding their wings closed and gently pressing the net fabric on them. Also, try holding the butterfly upside down;  it seems to calm them.

Keep the net closed so that other butterflies don’t fly out as you remove the one in your grasp, then pull out your catch and take a look.

Tracy Hamilton shows how to retrieve a Monarch from the net.

Tracy Hamilton shows how to retrieve a Monarch from the net.

4.  Examine butterfly, establish its sex.

This is when you examine the butterfly to determine its sex.   Open the wings gently and look for the two pheromone sacs on the lower half of the butterfly’s wings.  If you see two black dots, it’s a male.  If not, it’s a female.   Also note the state of the butterfly—is it

Male Monarch Butterfly

Male Monarch Butterfly: it’s a boy! See the two black dots on the veins of his lower wings? Those are pheromone sacks–supposedly they drive the lady butterflies CRAZY.

weathered and raggedy, or fresh and healthy?  If the butterfly is extremely worn out and highly unlikely to make it to Mexico, refrain from tagging it.  Let the poor creature fly off.  Note the info on your data sheet or notebook, as well as the tag number.

Raggedy Monarch butterfly

Raggedy Monarch butterfly. I don’t tag beat-up butterflies like this. Doubtful she’ll make it to Mexico. Plus, don’t want to waste tags.

5.  Remove tag from sheet and adhere to butterfly

Holding the butterfly between two fingers with wings closed with one hand, remove a Monarch Watch sticker from the tag sheet.  I like to use my thumbnail and get them on the tip of my nail so they’re easy to slip onto the discal cell of the butterfly’s wing. Some

Use your thumbnail to lift tag from sheet and transfer to butterfly.

Use your thumbnail to lift tag from sheet and transfer to butterfly.

people prefer a toothpick to lift the tag off the sheet. Try not to handle the adhesive too much, as it won’t stick to the butterfly’s wing as well if it has oil from your fingers on it.

Place the tag on the discal cell, as illustrated in the tagging sheet sent to you by Monarch Watch.  Press gently, but firmly.  Congratulations!  You’ve tagged a Monarch butterfly.

Press the tag onto the discal cell in the middle of the lower wing, as shown.

Press the tag onto the discal cell in the middle of the lower wing, as shown.

Make sure you’ve noted the tag number, butterfly’s sex, any other useful data, on your data sheet or notebook.

6.  Release

Open your grasp and let the butterfly go.  If you’re so inclined, send her off with a kiss and best wishes for safe travels to Mexico.

Off she goes!

Off she goes!

After the Monarch migration season, send all your data to Monarch Watch by December 1 so it can be entered into the online tag recovery database.   In the spring, you can check  to see if any of your Monarchs were recovered in Mexico.

Monarch butterfly recoveries

Of about 1800 Monarchs tagged, we’ve had 24 recoveries in Mexico.

Good luck with your tagging.  Please let us know how it goes.

Like what you’re reading?  Follow butterfly and native plant news at the Texas Butterfly Ranch. Sign up for email delivery in the righthand navigation bar of this page, like us on Facebook, or follow us on Twitter, @monikam.  You can also read our stuff on the Rivard Report.

31 thoughts on “Butterfly FAQ: How to Tag A Monarch Butterfly in Six Easy Steps

  1. Hey there! Great article on tagging Monarchs 🙂

    I do want to make an observation if that’s ok . . . it would probably be wise for people to use gloves and/or sanitize between taggings (maybe after every 5 or so Monarchs, not necessarily after each one). Here is the reason: this past winter I participated in a citizen scientist research program done through the University of Georgia. They had us collecting samples from overwintering Monarchs by gently rubbing their abdomens to collect any OE spores that might be present. I sampled 13 Monarchs, 12 of which were collected from the Riverwalk Milkweed patch in San Antonio. The data collected, q-tip and sticker samples were all sent in to the University of Georgia to be analyzed. Six of the Riverwalk Monarchs were HEAVILY infested with OE, 5 were moderately infested. The only one that did not have any OE spores was one I sampled in Plant City, FL (near Tampa). So, if people are out there tagging Monarchs and they get one that has OE, the spores will be passed on to any tagged afterwards. I really really think that people need to be very careful about this and not pass on any more of this virus. I was told that of all the Monarchs sampled this past winter over the southern states, that 45% of them were infected with OE.

    Anyway just thought you would want to know. Thanks for all your work! I love reading your articles 🙂

    • Hi Lisa,
      Thanks for the kind words and for writing.

      I don’t believe it’s necessary to wear gloves–that’s just my view and also that of Monarch Watch found Dr. Chip Taylor who replied when asked, “Never have. Never will.”

      I guess I feel like they are creatures in the wild and the wild is not sanitary. The strong will survive, and nature will take it’s course. If it were in a lab, that would be a different thing.

      Again, my opinion. Thank you again for reaching out. –Monika

      • Very late to reply to this, however this message is concerning..
        Monika, I can see why you would think that “…the wild is not sanitary. The strong will survive and nature will take it’s course.” could be applied here.. But it does not, because you are intervening with nature and not sterilizing your hands between individuals. Consider that you are handling one butterfly after another after another. This means that every butterfly touched after the first one will have artificially come into contact with the first butterfly just by being in your hands. You are therefore artificially putting these butterflies in contact with one another when they likely would never have come into full contact (especially with so many individuals, considering how many are handled) in the wild. If you really dislike wearing sterilized gloves and changing to new ones between each individual (I also feel wasteful doing this, so I can see that point), then a cleaning agent proven to work against OE that can be used in the field would be the best measure to reduce spread. It would be disappointing to think that by trying to help this species, humans end up causing further harm. Personally I would at least wash my hands very well between handling of individuals to decrease the chance of spreading OE.

        • I forgot to include an example for comparison, which would be WNS ( white nose syndrome) in bats. WNS may be a fungus, whereas OE is a protozoan, however they both spread through contact between individuals or individuals coming into contact with the same surface. A knowledgable bat researcher would never handle multiple bats with the same gloves if they knew WNS is a possibility in the population they’re handling.

    • You are correct, gloves should be used otherwise you are needlessly spreading OE. The “strong” will not survive if you are purposely spreading OE. Monarch lovers do their best to mitigate it.

  2. Hi I would like to ask you about the article on Catalina Trail. Please email me monique dot hennington at atcic dot org. Thank you in advance.

  3. Until I read this post, I didn’t know that anyone could tag Monarchs. I assumed it took special training. My husband and I ordered our tags and nets (arrived this week) and are looking forward to trying them out soon. Saw a Monarch in our backyard (Needville, TX) last week before we had the tags and nets, hopefully there will be more later. We will also be tagging Monarchs in Matagorda, TX where we spend the weekends. Matagorda is a coastal town and the Monarchs come through there every year, often roosting near the LCRA Nature Center.

  4. I would like to do this with my son but I think we might be too late in the year. We live in Travis County (Hill Country, TX will early November be to late?

  5. It is very easy to capture a monarch with a net. It is also very easy to catch one without a net. I capture many wild monarchs just with my fingers when they are nectaring on the milkweed. I use the toothpick method to attach the tags. I’ve been raising & tagging monarchs for several years………..

  6. I would like to report to whomever that most years the monarchs roost overnight in my yard, in the pine trees, in late fall. In the past I have not known who to report this to. When this happens again should I let someone know?

  7. You need to sign up on WWW. Monarchwatch.org. Then all you do is report when and where you see the Monarchs. and how many. Very easy and quite interesting.
    Thanks you for sharing

  8. We have been raising monarch caterpillers in science for a couple of weeks now, and i love it, it is so fun to raise then and i have went out and found some eggs and caterpillers and i have been raising some at home and i read your blogs ( i think thats what they are called) and i have learned so much from them they are so useful. Thank you so much

  9. Before walking 1,000 miles, how would you like a weight to be glued onto one of your legs with toxic adhesive? Tagging is cruel. Perhaps so few of your tagged monarchs were “recovered” because you handicapped them.

    • I agree with Cathee … the tags weigh about 2% of the monarchs’ total body weight. This would be analogous to gluing a four pound weight to one of my feet, before leaving on a very long walk, plus, the tags don’t flex and bend the way mother nature intended, so it’s really like gluing a four pound weight to one of my feet that also prevents me from flexing my ankle. Leave the poor little guys alone, so they have a chance to complete their mission.

      • The more I think about this, the more it bothers me. Individual monarchs vary in weight from about .25g to about .75 grams, making my previous analogy more like gluing somewhere between a 4 lb. and a 12 lb. weight to one foot, let’s call the average 8 lbs.. For reference, a gallon of water weighs about 8 lbs., so imagine gluing a gallon jug of water to only one foot. Now, the wings need to be extremely light and flexible, otherwise it would require far too much energy to overcome the inertia to flap them, so I’m guessing that most of the overall weight is in their body, and the wings are a small fraction of the total. Without capturing one and ripping it’s wing off to weigh separately, I’m only guessing, but I think it’s reasonable to assume that your tag may be adding nearly as much mass as the wing itself. I’m surprised the poor little guys don’t fly in circles after you tag them.

        • I had the same concern, so I weighed the tags. The tags I just received are 0.0008 grams each. That is about 0.3% of the mass of a small butterfly. That is like about 0.6 lb on a 200 lb person. Your clothes are much heavier than that.

          • The 2% figure is apparently wrong. The tags I got are much lighter. Let’s use milligrams instead of grams to make the numbers easier to read. I just weighed 3 medium sized monarchs, desiccated for 3-4 months. They averaged 150mg. My tags weighed only 0.8mg. That is only 0.5% of the mass of a dried butterfly. A newly “hatched” one, ready to take off the first time is much heavier and filled with fluid. Another site gives the range of 250mg to 750mg, making the tag less than 0.3% of the weight of the butterfly. On an average 500mg butterfly that is like a 200lb person being asked to carry 0.32 lb… 5.1oz .. the weight of a fat letter, not a gallon of water.

            And the wings are actually quite stiff, and the tags are placed relatively close to the wing hinge. So the inertia of the tag is low and it stiffens the wing at a point that should be stiff anyway.

            I watched about 200 fly away before receiving my first tags and I did not notice any difference in the behavior or flight pattern of a tagged butterfly vs and non-tagged one.

  10. Pingback: The Monarch Diaries-Adult (Part 3) | The Garden Diaries

  11. Hello, I have raised monarchs (along with other native b-flies for over 20 years), here in South Florida. I plan to start tagging my monarchs, right before I release the newly emerged ones. This will be a LOT less stressful than netting them 😉 You can find my releases and dedications on Periscope and FaceBook Live. >i<

  12. I have raised butterflies at two locations in Florida for over 20 years and still find them awesome. any contact of any living thing with any human is harmful to them and potentially lethal. How much do we need to know about them? Our sole duty is to supply them food and safe passage without endangering them. If there is any question just bug off, literally.

    • I decided against tagging. I disagree with you, June. If ten eggs are outside—MAYBE three make it to butterfly. I take those same ten, house them, protect them from tachnid flies, hunter bees, bufo toads, etc—EIGHT of those ten will emerge as adult butterflies! }i{ So, how is that endangering them?

      • I tag mine, but agree with Tina on endangerment. Only my gut says it is more like 3 out of 50 or 100 make it past the lizards, wasps, and all the other caterpillar-eaters. 8 out of 10 flying away is similar to my success rate raising them. And I released about 300 last year. That number of flying butterflies would have taken as many as 10,000 eggs left to nature.

    • My first reaction to this post was “everything eats them!” Then I thought of an interesting observation. I released a newly “hatched” one just after tagging. It took off, strongly gaining altitude, and passed by an oak tree. Out of the tree darted a bird … I though the Monarch was a goner… then about 2 ft from the butterfly, the bird wheeled around and went back into the tree. I can only assume that this “educated” bird had already eaten one and now associated the color pattern with unpleasant minutes puking his guts up!

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