Monarch Larva Growth

Monarch Larva Growth

From the pinhead pearly eggs, to the full grown larva...the young monarch caterpillar goes through amazing changes!

Hatching Monarchs

From the pinhead pearly eggs, to the full grown larva…the young monarch caterpillar goes through amazing changes!
When the larva is ready to move into the pupa (chrysalis) phase it will hang upside-down and molt one last time.

Hanging in a "J"

When the larva is ready to move into the pupa (chrysalis) phase it will hang upside-down and molt one last time.
After becoming a butterfly, the process begins again...

Laying Eggs

After becoming a butterfly, the process begins again…

The term “larva” refers to a growth stage of all insects with complete metamorphosis. The word “caterpillar” only refers to a butterfly or moth in this growth stage. So, its OK to use either word to describe a monarch after it hatches from the egg and before it moves to the pupa (chrysalis).  Most scientists use the term “larva.”

 

Raising Larvae

Rearing monarchs can be a fun learning activity for youth and adults, and can provide valuable scientific information if rearing data are collected and reported to citizen science projects such as the Burpee Monarch Project.  

You can become a part of our citizen science team.

In general, a monarch larva (caterpillar) can be kept safely in Burpee’s provided tennis ball cans, an aquarium, large jar, ice cream bucket, bug cage, or another relatively large cage. The container should be easy to open (you need to clean the frass (poop) out, and replace leaves frequently.  The container should have a screen covering or holes for air flow, and allow you to see the larva inside.

After the pupa (chrysalis) is made, the container should be large enough for the adult to expand its wings when it emerges. 

Quick Tips

  • Keep the cage out of the sun or other hot places (like car trunks in summer). High temperatures can kill the larvae.
  • Cages must be cleaned and larvae provided with fresh milkweed DAILY. 
  • Watch out for pesticides.  Dog Flea/Tick treatments, bug sprays, and other chemical that kill or disable insects are deadly for monarchs too.
  • Monarchs remain in the larval stage for about 2 weeks after hatching from eggs. During this time, they go through five instars, which means that they molt (shed their skin) five times.
  • While larvae are molting, they often crawl up the side of their container, and should not be handled during this time. If you look closely, you will notice when their old head covering is about to come off. You may be able to find this covering in your cage. They will eat the rest of their skin!

1st Instar

After hatching, the larva eats its eggshell (chorion). It then eats clusters of fine hairs on the bottom of the milkweed leaf before starting in on the leaf itself. The newly hatched larva will feed in a circular motion, often leaving a characteristic, arc-shaped hole in the leaf. You may notice that if you frighten 1st (and 2nd) instar larvae they will drop off the leaf on a silk thread much like a spider may do…and hang suspended in the air.  The easiest way to move a larva of this size is using a small craft paintbrush.

Body Length: 2-6 mm

Body Width: 0.5- 1.5 mm

Back Tentacles: Barely Visible

Front Tentacle: Small Bumps

Time in this larval stage is usually 1-3 days, temperature dependent. 

This newly hatched monarch has a black head and grey body.  There are no stripes.  The larva eats its own egg and then begins to eat the hairs of the leaf.

First Instar

This newly hatched monarch has a black head and grey body. There are no stripes. The larva eats its own egg and then begins to eat the hairs of the leaf.
hatching monarch

2nd Instar

The grey, transparent skin changes to  a clear pattern of black (or dark brown), yellow and white bands.  The triangular spots behind the head do not have the long setae present in the spots on the first instar larvae. The setae on the body are more abundant, and look shorter and more stubble-like than those on first instar larvae.  You will find the easiest way to move this size larva is with a small paintbrush.

Body Length: 6-9 mm

Body Width: 1-2 mm

Back Tentacles: Small Knobs

Front Tentacle: 0-3 mm

Time in this larval stage is usually 1-3 days, temperature dependent. 

The transparent, grey body has transformed to a small, striped larva.

2nd Instar

The transparent, grey body has transformed to a small, striped larva.
thumb 1408228621228 1_early_instar

3rd Instar

Through careful observation, one will see black and yellow bands on the abdomen of a 3rd instar larva.  The bands are darker and more distinct than those of the  2nd instar.  Bands on the thorax are still indistinct.  The first set of thoracic legs is smaller than the other two, and is closer to the head. 

3rd instar larvae usually feed using a distinct cutting motion on leaf edges. Unlike first and second instar larvae, third (and later) instars respond to disturbance by dropping off the leaf and curling into a tight ball.

Monarch biologist Fred Urquhart called this behavior “playing possum.” 

Body Length: 10-14 mm

Body Width: 2-3.5 mm

Back Tentacles: 0.9 mm

Front Tentacle: 1.7 mm

Time in this larval stage is usually 1-3 days, temperature dependent. 

With more prominent antenna and a larger body, the 3rd instar continues eating at an even faster rate than ever before!

3rd Instar

With more prominent antenna and a larger body, the 3rd instar continues eating at an even faster rate than ever before!
3rdinstar2 1

4th Instar

The 4th instar larvae have a distinct banding pattern on the thorax which is not present in 3rd instars.  

Body Length: 13-25 mm

Body Width: 2.5-5 mm

Back Tentacles: 2 mm

Front Tentacle: 5 mm

Time in this larval stage is usually 1-3 days, temperature dependent. 

This stage is marked by a new banding pattern not present in previous stages.  The larva will eat its own skin once it sheds.

4th Instar

This stage is marked by a new banding pattern not present in previous stages. The larva will eat its own skin once it sheds.

5th Instar

The body pattern and colors of 5th instar larvae are even more vivid than they were in the 4th instar.  There are distinct white dots on the prolegs, and the body looks quite plump, especially just prior to pupating. 

The 5th instar monarch larvae often chew a notch in the side of the leaf they are eating, which causes the leaf to fall into a vertical position. They move much farther and faster than other instars. 

Body Length: 25-45 mm

Body Width: 5-8 mm

Back Tentacles: 4 mm

Front Tentacle: 11 mm

Time in this larval stage is usually 1-3 days, temperature dependent. 

The body pattern and colors of fifth instar larvae are even more vivid than any other stage.  This is the largest stage and will end with a final molt into the pupa.

5th Instar

The body pattern and colors of fifth instar larvae are even more vivid than any other stage. This is the largest stage and will end with a final molt into the pupa.
larva J1