Waiting for Adults

While we continue to wait for the next generation, let's salute the monarch larvae. Most of the world's monarchs are in this stage right now.

Image of monarch butterfly larvae on flowering milkweed — "I have only seen a couple of single monarchs this spring but I found a caterpillar on my butterfly weed." Beth Rice of Chattanooga, Tennessee on May 7, 2017

Never Fewer Butterflies

Right now, the number of adult butterflies is at its lowest; at no other time of year are there so few adult monarchs.

With so few butterflies, the migration has come to a standstill. Look at the animated migration map and see how little things have changed. We're still waiting for the surge of 1st generation butterflies and this week was the slowest of the season. There were still people reporting faded-winged butterflies, which means that some of the monarchs from Mexico are still around.

New Generation Coming

People are reporting larvae — lots and lots of larvae. Eating and growing, today's monarch caterpillars will soon be northbound butterflies.

No to Neonicotenoids

Journey North participant Karen VanHees wrote with concern about plants being sold to butterfly gardeners that contain neonicotenoids, a class of systemic pesticides that are harmful to monarchs and other pollinators. The flowers are toxic, and so is the plant material that's eaten by monarch larvae and other herbivores. Watch out for neonicotenoids — and other pesticides — in any garden products that you purchase. If you're not sure, don't buy it. Read more:

Xerces Society: Neonicotinoids in Your Garden
Monarch Joint Venture: Insecticides and Monarchs
Xerces Society: Neonicotinoids and Bees

Old Generation Persists

New Generation Coming

No to Neonicotinoids!

What Do Monarch Larvae Do?

Crawling along a paper-thin leaf. Eating while hanging upside down. Monarch caterpillars defy gravity. What do monarchs do during the larval stage of the life cycle?

Monarch caterpillars eat voraciously. Find the two larvae in the photo. One is 2,000 times larger than the other. A monarch larva can grow this much in about two weeks, depending on temperatures.

Eat
Monarch caterpillars eat voraciously. Find the two larvae in the photo. One is 2,000 times larger than the other. A monarch larva can grow this much in about two weeks, depending on temperatures.

Monarch caterpillars grow through five stages as a larva. Each stage is called an instar. The smallest stage is the 1st instar. As the larva grows it goes through the 2nd, 3rd, 4th and 5th instars. After that, the larva becomes a chrysalis.

Grow
Monarch caterpillars grow through five stages as a larva. Each stage is called an instar. The smallest stage is the 1st instar. As the larva grows it goes through the 2nd, 3rd, 4th and 5th instars. After that, the larva becomes a chrysalis.

This monarch larva just shed its exoskeleton and is now eating the remaining portion, called the exuvia. A monarch must shed its exoskeleton to make room for growth. The process of shedding is called molting and happens between each instar. The most likely reason for eating the exuvia is to recycle the nutrients it contains, especially hard-to-get nutrients like nitrogen.

Molt
This monarch larva just shed its exoskeleton and is now eating the remaining portion, called the exuvia. A monarch must shed its exoskeleton to make room for growth. The process of shedding is called molting and happens between each instar. The most likely reason for eating the exuvia is to recycle the nutrients it contains, especially hard-to-get nutrients like nitrogen.

Monarch caterpillars have tiny, oval-shaped holes on the sides of their bodies. Dr. Karen Oberhauser explains what they are and how they work: “Monarchs ‘breathe’ through tiny openings on the sides of the abdomen and thorax called spiracles. The spiracles are in their cuticle, like our skin. I put quotes around the word ‘breathe’ because this is very different than the kind of breathing you do. Monarchs don’t have lungs. The air goes into their spiracles and through a whole series of tubes in the body calle

Breathe
Monarch caterpillars have tiny, oval-shaped holes on the sides of their bodies. Dr. Karen Oberhauser explains what they are and how they work: “Monarchs ‘breathe’ through tiny openings on the sides of the abdomen and thorax called spiracles. The spiracles are in their cuticle, like our skin. I put quotes around the word ‘breathe’ because this is very different than the kind of breathing you do. Monarchs don’t have lungs. The air goes into their spiracles and through a whole series of tubes in the body calle

Monarch larvae have two different kinds of legs, true and false. Like all insects, the caterpillars have six true legs. They are attached to the thorax. The false legs, or prolegs, are attached to the abdomen and are only present during the caterpillar stage. False legs have pads at the ends with sticky hooks called crochets. When you hold a caterpillar, you can feel the grip of the crochets. Crawling along a paper-thin leaf, or eating while hanging upside down, monarch caterpillars defy gravity.

Walk and Grip
Monarch larvae have two different kinds of legs, true and false. Like all insects, the caterpillars have six true legs. They are attached to the thorax. The false legs, or prolegs, are attached to the abdomen and are only present during the caterpillar stage. False legs have pads at the ends with sticky hooks called crochets. When you hold a caterpillar, you can feel the grip of the crochets. Crawling along a paper-thin leaf, or eating while hanging upside down, monarch caterpillars defy gravity.