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?

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.

Ready to tag some butterflies?

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.

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.

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. 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.

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: 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. 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.

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.

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!

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.

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

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