Raising butterfly caterpillars indoors is easy. There are tips, however, that can bring more success to your rearing success.
1) If you are raising caterpillars in a popup, aquarium, or other container and their food is not actually touching the bottom or sides of the container, move the vase/pot to the side. If a caterpillar crawls off the plant to molt, it may have trouble finding the leaves again if the leaves are not touching either the bottom, top, or sides of the container. Notice this photo. The plant isn’t touching the bottom or sides of the popup. Caterpillars could crawl about for hours without finding milkweed. Move the plant over to a spot where the plant will be touching the side of the popup. A caterpillar will easily find the plant as it crawls around the popup.
2) When walking in the woods or fields, mosquitoes and ticks can be a concern. Mosquito and tick borne diseases are no joke and can be deadly serious. Using a mosquito and tick repellent is highly recommended. But before you touch a butterfly, chrysalis, or caterpillar, WASH YOUR HANDS THROUGHLY! The repellent may not affect them. But it may kill them, depending upon the brand of repellent and species of butterfly or moth. The two main thoughts are a) protect yourself and b) protect butterflies and caterpillars. The biggest keys are to remember to spray on the repellent AWAY from any living insect or their plants and to wash thoroughly before touching anything alive or its food.
3) People who live in the southern states and in old houses often find it absolutely necessary to use insect spray. Ants, roaches, scorpions, and spiders like to move into our homes too. If you must spray, move your insects totally out of the house.
Recently I used an insect fogger for some moths in bird seed in my laundry room. The laundry room was 35 feet from the only container of caterpillars that I had in the house. Not only was it 35 feet away, it was in a totally separate room, a closed door and 35 feet separated the fogger and the caterpillars. I didn’t even stop to think of the duct work for our air conditioner (which cut on as the fogger was filling the room with insecticide). It wasn’t until it was too late that we noticed that the popup was covered with green vomit from sick caterpillars.
4) Disinfect rearing containers that you used in the past. Each group of caterpillars should go into a disinfected or ‘new’ rearing container. If you make a throw-away like the shoe box, don’t reuse it for another batch of caterpillars. They have horrific diseases! Remember, though, that when you have been handling diseased caterpillars, you transfer those germs to anything you touch, including the bleach bottle handle and lid. When you disinfect rearing containers, wipe down anything you may have touched with a bleach wipe or something similar, especially if you had disease issues with your last batch of caterpillars.
5) If it looks like something is wrong with a caterpillar, either euthanize it or raise it totally separate from your other caterpillars. Just like people, disease can be transferred from one to another. Nature has many unhappy surprises for caterpillars. Nature only allows 1 or 2 out of 100 to live to become adults. Disease is one of the reasons they die.
6) Caterpillars grow too large for their cuticle (skin). When it’s cuticle will not stretch further, the caterpillar molts (crawls out of its cuticle). If your caterpillar is off the plant and sitting still, leave it there. Do NOT move a caterpillar that isn’t moving on its own. Be aware some species can’t finish molting if they are moved. If they cannot finish molting, they will die. In most instances, Monarch caterpillars do fine if they are moved when they are molting.
7) Remember that petting a dog or cat with flea and tick medication before tending to your caterpillars can kill your caterpillars. The monthly medication will stay in the dog or cats skin oils and when you touch the pet, the medication (poison) will be on your hands. Wash your hands well ALWAYS before you feed your caterpillars or touch your caterpillars’ food.