When your caterpillars emerge from eggs or your caterpillar shipment arrives, check it immediately! DO NOT, I repeat,
DO NOT move your caterpillars if they are not moving their back legs (prolegs) on their own. Caterpillars
crawl out of their skin, about four times before becoming a chrysalis. The time period between molting is called an 'instar'. Monarch caterpillars go through five instars before pupating into a chrysalis. If you move your caterpillars while they
preparing to molt or in the process of molting, they could (but not necessarily will) die. Their skin never grows. As they grow, they must leave
their old smaller skin. To prepare for molting, they will suddenly stop eating and sit for a while
in one spot. They are preparing to molt. They will lay a silk pad and lock thier backlegs (prolegs) into
the silk mat. After about a day, they will split their skin at the head and simply slowly crawl out of thier
old skin. In most cases, they will then turn around and eat their old skin.
When caterpillars prepare to
molt, they draw thier heads out of their head capsules. When they start to molt, their head capsule pops off. Only when
caterpillars pupate will their head capsules says attached to their old skins. In the photographs below, notice
the size difference between the old head capsule and the new head capsule.
Photographs of molting caterpillars
It is best to place the container in which your caterpillars
arrive into the rearing container you have prepared. If you must move the caterpillars, tickle their rear ends. If
they move their back legs, it is safe to gently pick them up and move them. Remember, stay sterile. Wash your hands
throughly before touching your rearing cage or caterpillars!
Be sure to feed them enough to prevent them
from running out of food. Cannabalism is not uncommon when they are hungry. Their cut food needs to be dry yet fresh, not
wet with water on the surface of the leaves. If their cut food dries out quickly, make a 'vase' for it.
Wrap the cut stem of their food in wet paper towels
and wrap the paper towels in foil. Presto! This keeps the cut stems fresh and is easy to clean. Simply
toss in the trash. A container of water often results in caterpillars
floating in the water. Water pics, used by florists are also a great method to keep stems fresh. If you use
water pics, be sure to sterilize them between containers of caterpillars.
The size of the adult butterfly depends greatly upon the amount of food the caterpillar eats. If the caterpillar runs out
of food often, the chrysalis and the resulting adult butterfly will be smaller than it could have been.
If mold starts to grow in their container, be sure to clean it carefully. Wet food, overcrowing, running out
of food, temperature fluctuations of 15 degrees or so, and other stress factors can and usually will cause your caterpillars to succumb
to disease. At the bottom of this page are photos of diseased caterpillars and other signs of trouble you
may run into with your rearing. Don't dismay! Remember, these diseases come from the wild and are common in nature.
Some of these diseases are purchased by farmers and gardeners for use in home gardens, crops, or forests. If your
caterpillars become diseased, it doesn't mean you did something wrong. Be as careful as possible yet please do realize
that disease is normal in nature.
Caterpillar droppings are called frass. When caterpillars run out of food, they will often eat frass. It is important
to keep enough fresh food in thier container and to keep it clean and dry.