This is the plastic pet carrier that I move the caterpillars in when they are bigger. I have never had anyone escape out the top. If you are worried about this, though, you can put panty hose over the lid. They work very well. I have not felt the need to do this. I am sure since I have now said this, I will have escaped caterpillars all over my kitchen. I like these pet carriers because they are excellent for picture taking. It is hard for me to capture good pictures through mesh enclosures. I usually do not put more than 4 or 5 caterpillars in a pet carrier, so I have several of them. I got them for $5.00 a piece, so very worth it to me. They are also very easy to clean. I try to wipe all the frass (caterpillar poop) out of the containers every day. If you have a build-up of frass, the caterpillars may become ill.
Getting ready for a change...
When your caterpillars have finally eaten their fill of milkweed leaves, they will travel to higher ground to prepare for their big change. If they are in any kind of enclosure, they will climb to the top. They are preparing to hang upside down in a "J" formation. This is where it gets exciting!!!!
Out with the old and in with the new!
As the caterpillars eat, they will grow big and "juicy". As they grow, they will molt. They eat so much and grow so quickly, they have to shed their old skin. When they shed or molt, they enter a new instar. This is a picture of a caterpillar shedding it's old skin. After they sit awhile to dry, they will eat their old skin and then continue to chow down on the milkweed leaves.
Just hangin' around!
This is what the "J" formation looks like. The caterpillar forms a silky webbing at the top of the enclosure and anchors itself very well before slowly dropping its head down to hang. Once the caterpillar does this, it will no longer eat. It will never eat another milkweed leaf. It has begun an amazing journey into metamorphosis. The caterpillar will hang like this for not more than a day or so. It will then form a beautiful chrysalis.