Life Stages: Monarch Butterfly

The monarch butterfly is one of the most readily recognized and iconic butterfly species on the planet.  While for some insects we might not even know what the immature stage looks like, the monarch has been heavily researched for many years and we know more about how it develops from egg to adult better than most insect species. We have a lot of monarchs at the museum field station where I work, so today I’m going to share the life cycle of the monarch butterfly, every stage for this one.

All insects start off as eggs, so let’s take a look at a monarch egg:

monarch egg

The monarch eggshell (called the chorion in insects) is pale and heavily textured with intricate patterns.  However, unless you get a really good, up close look at one, you’re mostly going to see a pale off-white football shaped object stuck to the underside of a milkweed leaf.  They’re small, but still readily visible if you look closely.  The egg eventually hatches, and the first caterpillar stage emerges:

monarch first instar

Immature insect life stages are called instars and an insect will move from, say, first to second instar by molting its exoskeleton so it can grow.  The first instar larva of the monarch is quite small and looks different from the later stages in its development. They have entirely black heads instead of the striped heads they develop later and they’re largely translucent.  Eventually, they eat enough that they outgrow their first instar exoskeleton and molt into a second instar:

monarch second instar

Seconds start to exhibit the stripey heads and the coloration that people associate with monarch caterpillars.  They’re less translucent than the firsts and start to show the white lines that make up a large part of the pattern on the later instars. The tentacles that come off the front and back of the caterpillars begin to show. Second instar monarch caterpillars have longer tentacles in front and only tiny stubs in the back. Both sets of tentacles are much more pronounced in the third instar:

monarch third instar

Third instars have obvious back tentacles, but they’re still fairly short. Both sets of tentacles are much longer in the fourths:

monarch fourth instar

The tentacles on the front of the fourths are quite long, and about twice as long as those in the back.

The fifth instar is the last stage:

monarch fifth instar

The tentacles are very long on the fifths!  The caterpillars are also quite large, about the size of your pinky finger.  They also have the color pattern most people most associate with monarch caterpillars, black, yellow, and white stripes and a striped head.

Once the fifth instar caterpillar has eaten enough and grown to a certain size, it can pupate.  The caterpillars typically leave the milkweeds they feed on as larvae and find another location to pupate:

monarch pupa

Monarch pupae are gorgeous!  Their pale green coloration helps them blend in with vegetation.  They also have a line of metallic gold spots along one side.  As they get closer to emerging as adults, the color changes.  The exoskeleton of the pupa becomes transparent and you can see the black and orange of the monarch and the outline of different body parts tucked inside.

The pupal stage of insects is really pretty amazing, transforming an insect from a worm-like structure to something with wings (usually).  They’re essentially completely rearranging their bodies!  Eventually, however, they finish their adult development, crack open the exoskeleton of the pupa, and pull their adult body out.  They then pump hemolymph (insect blood!) into their legs, mouthparts, and wings to expand them to their fully extended form.  Then the exoskeleton “cures” and hardens.  Once that happens, the insect is as big as it will ever get and has all its body parts in the position they will remain the rest of its life:

monarch adult

The only change an adult undergoes is the loss of body parts.  With butterflies, you can often get a good idea of whether it is young or old by looking at the wings.  Complete wings with brightly colored scales tend to indicate younger adults.  Tattered or missing wings and dull spots where scales have rubbed off generally mean you’re looking at a butterfly nearer the end of its life.

Monarch males have scent glands that help them find their mates. Once they find a female, they will mate:

mating monarchs

The female then lays an egg on the underside of a milkweed leaf.  She will leave it behind to lay more, often on other milkweed plants.  The caterpillars that hatch have to fend for themselves and ultimately only a small percentage will make it to the adult stage.

Monarchs have a very complicated yearly life cycle.  I am not going to go into much detail here, but they have multiple generations a year.  The monarchs that fly north from Mexico typically make it as far as Texas before they lay a bunch of eggs and die. The monarchs that hatch from these eggs spread further north in search of milkweeds and nectar, and then they too lay eggs and die.  This can happen one or two more times before a special generation is produced in late summer or early fall.  This generation lives close to 6 months instead of just a few weeks and they are the ones that will fly to Mexico, overwinter there, and then fly back to the US in the spring.

So there you have it: the complete monarch life cycle – and the first Life Stages post.  Hope you enjoyed this one, and I’ll post another species soon!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth.

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Well-Nigh Wordless Wednesday: Giant Caterpillar of the Giant Leopard Moth

For the past two years, this has been the time of the fuzzy caterpillars. I’m used to seeing hundreds of furry little wormy guys hustling across the road at work and making their way through the grass.  This year, I’ve hardly seen any, but the best one was this impressive beast:

caterpillar

Giant leopard moth caterpillar, Hypercompe scribonia

That’s a giant leopard moth caterpillar, and they live up to the “giant” in their name!  That caterpillar was a good 3 inches long, and quite thick with all of those hairs circling its body.  Shortly after I took this shot, it curled up into a little ring in my hand, a defense mechanism they’re known for that tucks their soft underparts safely sway inside the stiff black hairs.  These caterpillars lack stinging hairs and don’t bite, so they rely on those hairs and the red bands between the hairs (warning coloration!) to deter predators.

Wish I’d seen more of these this year, but this has been a very strange year overall.  Here’s hoping things will be back to normal next year!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Well-Nigh Wordless Wednesday: Sluuuuuurp!

I was out with my intern a few weeks ago looking for caterpillars and showed her some spicebush swallowtail and black swallowtail caterpillars before we made our way to the pipevine to look for pipevine swallowtail caterpillars. She hadn’t ever seen the pipevines, so I pointed out a few and we started looking around to see how many we could find on the plants.  I peered into the leaves trying to find a big caterpillar that was about to pupate when I saw a really odd-looking, shriveled caterpillar.  I assumed it was dead, but when I looked a little closer it moved.  So I looked even closer and saw this:

Jumping spider eating a pipevine swallowtail caterpillar

If that spider could smile, it totally would!  He (or she) looked quite pleased with himself and was dragging the wrinkly carcass around with him as he tried to hide under a leaf.  He was NOT letting that thing go – it was probably the score of a lifetime!

Isn’t nature grand?

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Well-Nigh Wordless Wednesday: Nom Nom Nom

When I was a kid, I never would have expected that I would own a cell phone, that I would spend a lot of my time sharing things I write via the internet, or that anyone other than James Bond could capture videos with a tiny device that you could hold in your hand.  Younger me carried an enormous 126mm camera around with her, took 3.5 inch square photos, and had to take them to a drug store and pay someone to have them developed.  Take a moment to appreciate this fact: we can do truly magical things with our phones!  Case in point, I took this video last week to test out Instagram’s new video function.  A cell phone, an inexpensive macro lens attachment, and a woolly pipevine plant, and here’s what you get:

That’s a pipevine swallowtail caterpillar, munching away on its host plant.  How awesome is it that we can do this sort of thing with our phones??

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Well-Nigh Wordless Wednesday: Silhouette

I took my camera out after work a few days ago to document the pipevine swallowtail caterpillars on the pipevine. It was a cloudy, rainy day (like most days recently), so I snapped one shot of a caterpillar against the clouds. I rather liked the way the insect is silhouetted against the white sky:

Pipevine swallowtail caterpillar, Battus philenor larva

Pipevine swallowtail caterpillar, Battus philenor larva

It was fun to get a white box style shot in nature, so I think I’m going to try to do some more of these!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth.

Well-Nigh Wordless Wednesday: Something in My Shirt

Ever find yourself sitting at your desk, chipping away at e mail responses after everyone else has left for the day, only to feel something moving on your back?  It happened to me a few weeks ago.  I sort of swatted at my back with my hand and the movement stopped, so I assumed I’d squashed whatever it was.  A few minutes later, however, there it was again, a little movement of something up my back.  I swatted again, it stopped again, I once again hoped I’d gotten whatever it was.  Nope!  Soon enough, whatever it was was crawling up my spine, which I have to say is a deeply disturbing feeling.  So, I pulled the whole shirt off.  Inside, I found this:

inchworm

Inchworm!

An inch-long inchworm!  I was a little shocked it was so large, but apparently you can get large caterpillars down your shirt when you crawl into bushy trees at work.  After putting the shirt back on, I took the inchworm outside and snapped a few photos with my iPhone before going back to blissfully inchworm-free work.

On a completely unrelated note, I think I will be able to get back to my regular blogging schedule soon!  Woo!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Well-Nigh Wordless Wednesday: Surprise!

The last evening of Bug Shot 2012, I was in the “toy room” helping clean up.  I had set up an aquarium for photographing aquatic insects the first night and hadn’t put it away, so I scooped everything out of it and was about to pick it up and dump the water out when I saw this clinging to the outside:

curve lined owlet caterpillar

Curve-lined owlet caterpillar

What a crazy cool caterpillar!  I believe it is a curve-lined owlet caterpillar, Phyprosopus callitrichoides.  It comes as no surprise that this is a woodland species.  Can you imagine how hard it would be to see one of these on a tree?!  I happily snapped a few shots, then I took it outside before I finished my cleaning.

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth