Rainy days and Sundays always get me down when I can not garden!

Monday, November 20, 2017


It all began on August 10th when I spotted a female monarch fluttering about my milkweed. I had started growing milkweed several years earlier when I first became aware of the decrease (90% over a span of two decades) in these beautiful Lepidoptera. As many of you may know, milkweed is the only host plant for monarchs. (Host plants provide a place for the female to lay her eggs and the food source for the caterpillars.) I figured by growing milkweed I was doing my part until I heard about “cat mammas”, individuals “collecting” and “raising” monarchs indoors. Monarch eggs are very small making it hard to spot them, however, watching a female lay her eggs you need only to wait and collect the leaf once she is finished! As I learned later, it may also ensure that the egg/caterpillars are not parasitized by the tachinid fly. So there I was collecting the leaves and bringing them inside the house, and even though I had already read up on the process, I was on a crash course in learning how to raise monarchs!

DAY 0-5 EGG  

The female monarch can lay between 100-500 eggs in her lifetime. She prefers younger plants or the newer leaves towards the top of older milkweed since they are easier for the cats to eat. She deposits one egg to the underside of the leaf securing it in place with a “glue” like substance. The egg is cream colored with distinct ridges, measuring 1.2mm high and .9mm wide. From the time the cat emerges from its egg it begins to eat, starting with its own shell!


Monarch cats are born to eat. They have a voracious appetite resulting in a 2000%+ increase in their size over a two week period. And with all this eating there is a lot of frass (poop)! During the larval stage the cat goes through five growth spurts or “instars”. (At the first instar the cat is between 2-6mm and by the fifth instar 25-45mm).  Each instar takes between one and three days to complete with the exception of the fifth which can take three to five days.  Temperature, humidity, light and quality of food effects this growth rate.  With each growth spurt stretch detectors signal that a newer, larger skin is needed. The period between each instar is when the cat molts or sheds. Shortly before molting your cat may not eat, remain still or wonder off. When its ready the caterpillar spins a bed of silk on which to anchor itself. This liquid silk is produced in the salivary gland which is excreted through a tube-like structure called a spinneret, located in the caterpillar's mouth. The head capsule is expelled first and then the cat wiggles/walks out of its old skin. Once out, the cat, you guessed it, eats the newly shedded skin!

By the fifth instar the caterpillar has grown to about two inches in length and has become rather plump. Once again, when ready, it will stop eating and wonder off. This time however, its looking for a safe place for its final transformation. This will typically be at the top of your enclosure.

DAY 15-19 “Hanging Out”

Once a cat finds a safe place to hang out it will weave a patch of silk for its final anchor. It will then turn around and grab on tight to this silk pad with its rear clasping hooks. The cats life may very well depend on this “death grip” since falling would most likely injure/kill the caterpillar. While hanging they look like a “j” and will remain this way for one to two days. The cessation of the “juvenile hormone” triggers the caterpillar to shed its exoskeleton and reveal the pupa or chrysalis. When this happens they wiggle, twist, jerk and squirm their way out, splitting the skin from the head to the rear and finally breaking the ligament that is holding the skin to the pupa. This time they do not eat the skin and you can usually find it at the bottom of the enclosure. The chrysalis starts out soft (and should not be handled) but will harden over time to form a protective shell. If you need to move a chrysalis for any reason its best to wait a few days.


Anticipation, and like a nervous “cat momma” I wait, and wait and wait. It takes about two weeks for a monarch caterpillar to rearrange all its parts and “eclose” (emerge) as a beautiful butterfly. Shortly before the butterfly is about to make its debut the chrysalis becomes transparent and the pupa darkens, making it possible to see the outline of the wings. Once out of the shell, the butterfly hangs upside down so that fluid (hemolymph) can be pumped from the abdomen to their crumpled wings, forcing them to stretch out and expand. If either or both wings harden before fully inflated they will be unable to fly. This process takes between 30 minutes to several hours and the butterfly should not be handled (if possible) during this time. In addition to their wings, the tongue (proboscis) which is in two halves must fuse together to form a tube. The monarch will extend and retreat the two halves until it becomes one. Failure to do so will result in the monarchs inability to take in nectar.


The average life of an adult monarch is 2-6 weeks during the summer. They mate within days of emerging and the female immediately begins to lay eggs. It is possible to have multiple (2,3,4) generations in a single summer. The exception are monarchs born in late summer which do not mate but travel (the great monarch migration) to their winter destinations of Southern California (western monarchs) and Mexico (eastern monarchs). Here they will over winter in a semi-dormant state until they begin the process all over again in the spring!

There is about a 10% survival rate from egg to butterfly in the outdoors. However, there's an upwards of 90% success rate with monarchs raised indoors. Here are a few things I learned along the way.

  1. Grow your own milkweed and have plenty of it. Cats need fresh leaves almost daily void of any pesticides. It also suggested to rinse the leaves with a water prior to feeding them to your cats.
  2. Have the correct raising cages designed to keep the cats safe, provide adequate ventilation, light, humidity and are easy to keep clean.
  3. Although its no guarantee, starting with eggs or very small cats (first and second instar) reduces the chance of the cat being parasitized by tachinid flies.
  4. Cats are very sensitive to a magnitude of ingredients and when they come into contact with them or are poisoned they throw up a green liquid. Keep your raising area chemical free and off limits to all potential hazards including pets.
  5. To avoid smaller cats from becoming lunch for larger cats (fourth and fifth instars) keep them in separate containers. Do not overcrowd your enclosures and keep butterfly’s separate from caterpillars. If you suspect that a cat is sick, separate it from the others.
  6. Clean cages daily of frass.
  7. Wash and rinse hands well before and after handling milkweed*
  8. Learn to recognize common monarch diseases and parasites. However if already sick, the chances of survival are slim.
  9. Be prepared to euthanize sick cats and/or butterflies if necessary.

Out of the eleven I started with from either eggs or very small cats, eight made it to adulthood (73%). I released my first butterfly, a male, on September 11.

*One final note, the sap of milkweed can cause atopic dermatitis, inflammation, pain swelling, burns and corneal damage to the eyes. Be very careful when working/handling it.

No comments:

Post a Comment