Queen, Monarch Caterpillars and Butterflies: How to Tell the Difference

Found a Monarch caterpillar on my milkweed!

                               –my friend Hugh Daschbach, via text message

How to tell the difference between a Queen or Monarch caterpillar

Every year around this time as the Queen butterflies start to show up, we get lots of questions about how to tell the difference between Queens, Danaus gilippus, and Monarchs, Danaus plexippus.  And with the warm weather that has gripped South Texas throughout November and now December, many of us are still finding eggs and caterpillars in the leaves of our milkweed.   Queens are here en masse.

Three Queen butterflies

Queens have been flying and reproducing this Fall.

As it turned out, the caterpillar in question that my friend Hugh texted me about (excuse the typos) was in fact a Queen.  The giveaway:  it had three sets of protuberances–frequently called antennae, but actually only one set are antennae and the other two are filaments.  The antennae have special sensing properties while the filaments are mostly for show, and to throw off predators.

Queens on Purple Mistflower

Queens on Purple Mistflower

Hugh’s confusion is common:  because of their similar color, size and affinity for milkweed as a host plant, Queens and Monarchs are often mistaken for each other in their various life stages.

But once you look closely, it’s not that hard to tell the difference between Monarchs and Queens.

First, Queens appear solid orange compared to the varying shades of a Monarch.  In the photo above, notice how with their wings folded, the Queens’ solid dark orange is interrupted with occasional white dots–nothing like the striking stained glass veins and color pattern of the Monarch below.

Resident Monarch butterfly on the San Antonio River Museum Reach

Monarch butterfly on the San Antonio River Museum Reach

With their wings open, the difference is even more obvious.  The Queen is solid, the Monarch has varied coloration.  Both of the examples below are male butterflies, as you can see by the prominent display of their family jewels–the defunct pheremone sacs that presumably once drove the lady butterflies wild.

Queen butterfly, wings open

Queen butterfly.  It’s a male.

Female Queens and Monarchs don’t have these prominent markings with wings open.   In Monarchs, the black veins are generally wider and more pronounced in the females.

Monarch butterflies are on the move in Texas

Male Monarch butterfly.  Notice the two dark spots, his “family jewels.”

In the caterpillar stage, the most obvious difference is that Queens have one set of antennae and two sets of filaments, while Monarchs have one set of antennae and one set of filaments. Antennae are on the head of the butterfly, while filaments are at the rear–and in the case of the Queen, in the middle.

Queen caterpillar with three filaments

Queen caterpillar sports three sets of protuberances–two sets of filaments, one set of antennae.

Notice in the photo above, the Queen has what appear to be THREE sets of protuberances.  The Monarch caterpillar only has TWO.  Both wear distinctive yellow, black and white striped suits.   The Queen often will have a slight red blend as the filaments connect to the caterpillar’s torso.  The patterns of the stripes can vary depending on time of year, humidity and diet.

Monarch butterfly caterpillar has two filaments

Monarch butterfly caterpillar has one set of antennae, one of filaments–two total sets.

Scientists don’t fully understand the biological purpose of the filaments, which seem to reach out and “feel” the universe around them.   They swerve and turn in various directions, almost punctuating caterpillar moves like a roving eye or arched eyebrows on the human face.

For the sake of identification, let’s just say their purpose is to signal the difference between Queens and Monarchs.   For more on filaments and what we do and don’t know about them, check this link on the Monarch Watch page.

Queen and Monarch chrysalises

Queen and Monarch chrysalises. Monarch in the middle.

In the chrysalis stage, Queen chrysalises are almost identical to Monarchs, except they are generally smaller.  They also sometimes offer a subtle pink hue, as evidenced in the picture above, Monarch in the middle, Queen on the sides.

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Let the Royal Butterfly Parade Begin: First Come the Queens, with Monarchs to Follow

We start seeing Queens in August, and this year is no different.  Queens, Danaus gillippus, share the multiple charms of Monarchs, Danaus plexippus.  Both flaunt large size, flashy, striped caterpillars and chrysalises that resemble a jade crystal flecked with gold.

Queens are back in town

Queens are back in town. Here, on Butterflyweed, Asclepias tuberosa.

If you’re lucky enough to have flowers blooming these brutal summer days, you’re likely seeing the burnt orange creatures.  Like Monarchs, Queens lay their eggs only on milkweed, but they nectar indiscriminately.   We had a few pass through our urban front yard garden this week, nectaring on lantana, Tropical milkweed and their favorite, Gregg’s purple mist flower.

Male Queens LOVE purple mistflower

Male Queens LOVE purple mistflower.

If you want Queens in your garden, we recommend planting mistflower. The bloom of the mistflower contains a special alkaloid that male Queens ingest, sequester, and later release as an aphrodisiac to attract females.

Distinguishing Monarchs from Queens can challenge butterfly observers. They appear identical on first glance, but look closely and you’ll see that Queens are a solid dark orange,  with wings folded.  Monarchs have much more variation in their coloring.   With wings open, the difference is more striking.  Queens

Queen butterfly, wings open

Queen butterfly wings open.  This one’s a male.

display none of the “stained glass” veins of Monarchs (see the banner photo at the top of this web page).  Queens’ open wings boast a solid orange-brown, with only white specks on the outer edges and a black outline.

In the caterpillar stage, Queens flaunt similar Monarch-like yellow and black stripes, but they also sport three sets of filaments, the amusing antennae-like protuberances that seem to feel the world around them in expressive contortions.  Monarchs display only two. Queens also wear a red accent where those filaments connect to the caterpillar, presumably a warning sign to predators.

Queen caterpillar with three filaments

Queen caterpillar with three filaments. Monarchs only have two.

As a chrysalis, Monarchs and Queens could be twins, except that Queens are slightly smaller.  Both attach themselves vertically from a a horizontal surface with a silk button after forming a “J” shape, then spin a shiny green chrysalis flecked with gold dots.  While

Queen and Monarch chrysalises

Queen and Monarch chrysalises. Monarch in the middle.

some butterfly species opt for disguises verging on the disgusting in the chrysalis stage–as bird droppings (Red-spotted Purples) and dried crinkled leaves (Gulf Fritillaries)–Queens and Monarchs win the chrysalis beauty pageant.  Their fantastic jade coloring and intriguing gold flecks provoke some folks to wear them as jewelry.  (Not something I recommend.)

For more tips on how to tell the difference between Queens and Monarchs, see these blogposts from the Texas Butterfly Ranch archives:

Queen Butterfly or Monarch Butterfly? Sometimes it’s Hard to Tell the Difference
How to tell the Difference between Future Monarch Butterflies and Future Queen Butterflies, Part II
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.