See the icky poo? There are a couple of other nearby plants with the same giant bites taken out of them, but clearly whatever it was it liked pesto best. I don't share well! Especially not the basil!!! un There is a chicken wire fence around the bed, so I'm having trouble figuring out what did this and how to dispose of it.
Do hornworms eat basil? The frass looks kinda like from hornworms. Look around, CAREFULLY, including on the undersides of all leaves/branches (incl. nearby plants).
At any rate it is *some* sort of insect doing the damage, so the chickenwire fence is of no help.
Looks like an "inchworm". (Inch or less long guys that are thin, and "inch along.") If the excrement is glistening, you probably still have the culprit there.
Pat's right about the back of the leaves. Try giving the "branches" a little shake and see what falls off. Then you can search for hangers on.
Yes, you'd be amazed how much excrement the can leave.
We have long furred ones here which are not good for the chickens. In fact, no bird I've seen will eat them. I don't know about yours, but maybe they shouldn't be chicken food.
Also, I don't know if it applies to this one, but I looked up the problem with some "furred" caterpillars, and found this. Better safe than sorry until it's ID'd for sure:
"Caterpillars or larvae of certain moths possess stinging hairs. These sharp hairs or spines are either hollow, connected to poison glands (venom flows on contact), or similar to glass fibers (hairs break off in skin easily) sometimes causing pain like a needle prick. Depending on the individual, reaction to the sting ranges from mild, with local reddening, swelling, burning and itching to severe pain. Hypersensitive persons may experience severe swelling, nausea and generalized systemic reactions, occasionally requiring hospital treatment. In severe cases, entrance of hairs into the eye can cause blindness.
Stings generally occur when accidentally brushing against one of these caterpillars or attempting to remove it by hand from clothing or on the body. Fortunately, stinging hair caterpillars are not a widespread problem (occur in small numbers). Most are found on corn leaves, vegetable plants, shrubs and trees."