Looks like one of the cabbage 'worms ', to me. Perhaps the most common of them all....the Imported Cabbage worm. (I'd need a better picture to ID which species, but it doesn't really matter that much.)

Bt-k is a very effective biological control agent used to control caterpillars. Only caterpillars. It does not harm any other kind of insect, birds, earthworms, fish, pets, or you.

The problem is that Bt-k (Bacillus thuringiensis-Kurstaki) is most effective when applied while caterpillars are very young. Smaller than what you've shown us.

Of course, you could very well have a big crop of youngsters going unnoticed....baby caterpillars are very small. I'd apply Bt at this point, and continue hand removal.

Next season, you might consider excluding the pretty white butterflies from laying their eggs.

cutworms are usually the color of your soil ...

as they live in the soil.. only coming out to eat ...

yours is most likely ... the color of the crop it is feasting on ... and why rhiz probably suggests one of the cabbage type plants ... or in this case.. probably your broccoli ... [cabbage.. broccoli.. what the difference .. bug-wise i mean]

to hide properly.. they have to look like what they eat.. or they will be eaten themselves ...

since it october.. not much need be done ... i surely wouldnt spend money on prevention .... nor eradication..

and as usual ... bug populations ebb and flow over the years.. so it not even necessary.. that they will be there next year ...

i would simply do a late fall thorough cleanup ... to get rid of any laid eggs ... and wait and see what happens next year..

let me put it this way .. if there was so little damage.. that you didnt even notice it.. until you found the bug.. then the population is so small.. that no reaction is required on your part.. IMHO ...

ken

The imported cabbage worm feeds on a wide variety of garden plants, including the broccoli and radishes mentioned by the original poster. There are several generations per growing season and a garden can quickly be reduced to green stems. The fall generation of caterpillars will pupate either on the plants or in nearby debris. They will overwinter as pupae, emerging in the early spring as butterflies to mate and begin laying eggs on the newly planted crop. Thus, performing a good fall cleanup is important for control...as is covering the plants with light weight garden fabric or even tulle from the fabric store.

Thank you for the advice.. this is very helpful.. a few follow up questions... should I move the lavendar that I have growing right outside the raised bed (I am guessing that those "white butterflys" hanging out on the lavendar are responsible for some of these cutworm invasions).

When you say fall clean up... I take it you mean I should throw all these eaten crops far far away and that I should not add this stuff to my compost pile. For the fall I was going to add a few inches of mulched fallen leaves to this raised bed to cold compost over the winter... would this help to suffocate the eggs? (I can easily put fabric cloth over the entire thing).

Thanks!

These are NOT cutworms. They are cabbage worms.

The white cabbage butterflies may simply be nectaring on the lavendar. Like all butterflies, they use all kinds of flowering plants as nectar sources.

I'd rake away any old mulch when you do your gardening cleanup. If your compost pile gets nice and hot, you could add the plant debris....otherwise bag it up and dispose.

Landscape fabric is not a good idea.