Tomato hornworms are entirely green in appearance. ... If you are a gardener, and if you ever spot a hornworm sporting these white spikes, then you should not kill them, but instead let them die on their own. These white protrusions are actually parasites. To be more clear, these parasites are braconid wasp larvae.
Are Hornworms good for the garden?
There's no question that tobacco or tomato hornworms can devastate your vegetable garden. A single big hornworm can strip a tomato plant of its foliage in a day or two. They generally start near the top and work their way down. Their camouflage coloring makes them very hard to spot, but their appetite gives them away.
What are Hornworms good for?
Hornworms are perfect for the fussy eater and are known to be the 'magic trick' to end a reptile's hunger strike. Not only are they an enticing blue-green color but they are very high in water making them a great way to rehydrate your animal.