A little later you can see them rearing up high to spin a cocoon on the back of the hornworm. There is no need to be afraid of tobacco hornworms they are harmless and can not sting. You can see them by naked eye. After you learn what the wasps look like, you will be surprised how often you find them indoors and outdoors. A glass jar with a lid of fine cloth held in place by a rubber band or canning ring makes an ideal cage for holding and rearing insects.
Nylon stocking makes a good cover for the jar.
If you collect and rear insect larvae by feeding them leaves from the same plant on which you found them, you will usually learn what type of adult they become. You will find many of the caterpillars fail to become adults because they already were hosts of tiny wasp grubs when you collected them. There are dozens of species of such tiny beneficial wasps. Using nylon stocking to cover the jar will admit plenty of air to reduce disease problems and prevent tiny parasitoids from escaping. Frequently, insects you attempt to rear will die due to diseases such as baculoviruses.