The photograph above is an example of one of the reasons I bring small caterpillars into the safer environment of the porch to mature and form their chrysalis. The caterpillar in the photo is a tomato hornworm. Tomato hornworms are extremely destructive in the garden. They can strip a plant in just a few day's time. That's the down side, on the up side, tomato hornworms turn into the delightful hummingbird moth. If you've ever witnessed one of these beautiful moths hovering over a nectar flower you will have most likely been entranced by the beauty and grace of it.
The white cocoons on top of the tomato hornworm are braconid wasps.
These wasps are a natural parasitical control, and the caterpillar is the host. I captured an image of the wasps in the photo just as they began to emerge. They are also a natural control for Eastern Tent Worms and other destructive pests. I have mixed feelings about the wasps. I love hummingbird moths, but have also seen de-foliated trees destroyed by tent worms.
The wasps will sometimes feed on swallowtail caterpillars too. If I move the caterpillars to a protected area when they are newly hatched they have a better chance of surviving to adulthood. I have tomatoes and certainly don't want them defoliated by a tomato hornworm, but I also admire the beauty of the moth they turn into. If I find a tomato hornworm I'll probably try to bring it to maturity. I'd like to have a few more hovering over my flowers, but will I keep a close watch on my tomatoes for hornworms...you betcha!