What's pestering my plant?

Find the Nature Spotter App. You send a picture, andget an email in response.

Could very well just be the beginning of a monarc butterfly.At first I thought gypsy moth but I have not known them to be all green. Are they eating your plant or just hanging about?

Monarch butterfly caterpillars are black and yellow. Don't know what these are, sorry.

its called a winter moth and can be killed with diatomaceous earth.

https://g.co/kgs/pwvjte

I have these on my tomatoes.

i don't think that they are tomato hornworms either. But BT is effective against them, so is picking them off. If you see one with tiny white eggs up and down it's back...do not destroy...that's a natural predator wasp doing the job.

not sure what it's called but it ate everybody's parsley last year. After they ate all the greens and moved on, the plant came back even healthier 😊

"They ain't no butterfly". Could be 'bag worm' check to see if you have any large 'nests' high up in the branches of your trees.

Last year I had caterpillars all over my parsley (I counted at least 30 of them) and thought they were monarchs but found out they were actually black swallowtails. Swallowtails love parsley and ate my whole plant which came back this year. I did not try to remove or kill any of them even though they were destroying my parsley.

http://www.butterfly-fun-facts.com/butterfly-species/butterflies-a-e/checkered-white-butterfly-pontia-protodice/ This is your culprit, they love alyssum, which is what yours is hosting on! This link shows you proof!

Yes, it's Nature Spotter.

It's not a tomato horn worm, Its to small. If you can, Take one off. And take it to your local garden center.

I bust open nest & let birds eat them,,,,...

Thanks for all the helpful answers everyone! I believe the culprit has been identified as the checkered white butterfly. I'm going to go do some research on this guy now.

Y'all are the best!