Tiny green worms on broccoli leaves?

[Troutslayer]

What kind of worms/caterpillars are these? Would BT do the trick?

[GardeningCook]

Yup - Bt asap - either spray or dust.

Next time you plant any brassica, you may want to look into using insect-weight floating row covers at planting time. Since brassicas don't require pollination, you can leave the row cover on 24/7 for the entire season (except for brief checks to be sure everything is A-Okay).

But for now - Bt it definitely is.

[Troutslayer]

Thank you for your input, I will look into the row covers.

[GardeningCook]

Keep in mind that you DON'T want to use the row covers now, since the caterpillars (& most likely more hatching eggs) are already on your plants. If you put row covers on now, all you'll be doing is trapping the pests into their own little hotel-with-buffet. It has to be Bt now; row covers the next time you plant seeds &/or transplants.

[imafan26]

Those are cabbage worms. They are the larva of a white butterfly with a black dot on the wing. Row covers help before the eggs are laid, but hand pick them and use Bt (dipel or thurgicide) dust over and especially under the leaves. It is a bacteria so it is organic and specifically targets caterpillars. The caterpillars will voraciously eat holes (big ones throughout the leaves in a very short time).

Cabbage worms will attack anything in the cabbage family.