Ther are two kinds, The cabbage worm adult is ehiyish butterfly, The cabbage looper adult is a moth. Both are easily controlled with Bt ( Dipel or Thuricide)

Here is a link that might be useful: Cabbage worm

Yes, I concur: Bt is absolutely THE best remedy. Here is an excerpt from the Q &A at You Bet Your Garden, hosted by former Organic Gardening editor Mike McGrath:
... spray the old original form of Bacillus thuringiensis...while the caterpillars in question are actively eating... DonÂt worry about that panic-inducing name  most people just call this organic pest killer by its initials: "Bt" , with a letter added at the end to indicate what strain or variety it is. There are currently three different Bts, each affecting a different type of insect pest. The one that stops caterpillarsÂALL caterpillars, by the way, not just ones that build little homes in your treesÂis the kurstaki strain, "BTK".
One of the oldest, most effective, and easiest to find tools in the organic arsenal (its been in use for close to 40 years), BTK is a naturally occurring soil bacteria that just happens to be deadly to caterpillars. ItÂs available from Gardens Alive and other natural gardening product suppliers, and at most garden centers (retail brand names include Dipel, Green Step, and Thuricide; ingredient labels should say ÂBt or BTK). DonÂt be surprised if a store keeper thinks it IS a chemical; BTK is used by lots of farmers to protect their sweet corn from tip-eating earworms, often without their knowing its one of those high-faluttin organic things!

When pest caterpillars chew on Bt sprayed leaves, their stomachs stop working and they soon die. Bt has NO effect if you spray it while theyÂre not eating, like in the winterÂthey must be actively feeding. And Bt is one of the safest things you can use. It will not harm you, your pets, earthworms, or beneficial insects. Birds could eat caterpillars that just ingested Bt and the birds would not be harmed. You wonÂt even hurt the caterpillars of pretty butterflies when you use Bt, because those caterpillars are feeding on weedy looking plants in the wild, not your tree leaves. (The only butterfly caterpillars that do appear in any kind of garden situation feed on carrots and parsley plants.)

There also is a strain of the bacteria that is effective against the Colorado potato beetle. Be careful, though, to get the strain that is NOT bioengineered!
Several biopesticide products based on the bacterium Bacillus thuringiensis (Bt) have become available in recent years. M-OneÂ, made from B. thuringiensis ssp. san diego, is genetically engineered and therefore is not allowed in certified organic production. NovodorÂ, produced by Valent USA Corp. (20), contains B. thuringiensis ssp. tenebrionis, a form of Bt that is not genetically engineered and can be used by organic producers in most states. One source of Novodor is Peaceful Valley Farm Supply.
http://attra.ncat.org/attra-pub/coloradopotato.html

cabbage loopers - a search here using that term will provide much info - are easy to control as already mentioned. He is calling them "worms" - they are caterpillars. ;) No real problem with BT use.

Dave

I'm going to try growing broccoli for the first time this year. I've decided to use ultra-light row covers on the plants to prevent the moths from laying their eggs. If that doesn't work, then I'll try the Bt. Just a personal preference on my part (I'd rather have none to begin with than have to spray when they are already on there). I got my row covers from Gardens Alive.

Both BT and floating row covers work well. You might also want to encourage paper wasps on your property. Two years ago, my paper wasps controlled the cabbage worms for half the season. Last year, I saw tons of butterflies, but very, very few worms (and those I saw were dead and parasitized by Apanteles glomeratus, a parasitic wasp). The paper wasps kept them under control the whole year. I didn't have to do anything. It was great!

Bellatrix

bobboberan,
Here in Z4,
I've found that if I get cauliflower and broccoli into the garden early(4-5week old transplants-puts it first week of May for Z4), I avoid the first flight of the cabbage moth.
My second planting July 1-ish needs to have BT applied to the plants... sometime early Aug.

I too find that early plantings HERE in the spring are not bothered by the worms, but fall plantings are heavily invaded.

I handpicked 15 off my cole crops today. I don't use bt because I do have lots of butterfly caterpillars on my asclepias and other plants, but if unchecked, one cat will clearcut a broccoli or cauliflower. I've also learned to plant densely and thin out the more damaged ones. The aphids are a pain too, because they can hide in the curled leaves and do serious damage before i can notice and spray them with soap.

I use floating row covers over all of my cole and greens crops and they work beautifully - zero worms. Since they require no pollenation, the covers can remain on until harvest. They have also prevented damage from rabbits for me - just make sure the edge is against the ground and tight. I get about three seasons out of them.

it sounds like its going to be alot of work I know they take up alot of room but how much room , and is one 1 foot by foot square enough per plant ?

They grow larger than a foot so that is pretty close to get large heads.

Bobboberan, I plant broccoli about 19-20 inches apart in 3 foot rows because as Wayne stated it gives them more room to grow and produces larger heads. On the other hand, I was speaking to a local farmer who plants and sells broccoli at the local Farmers Market. He plants Packman broccoli in double drill rows with plants about 10-12 inches apart. If you do plant 1 per square this might be the cultivar to plant.

Packman gets fairly large and it does have sideshoots altho not as many as some cultivars. For one foot spacing I would look at a smaller plant like Small Miracle.
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Cabbages, the pointy headed cultivars are less space demanding. Point One, Jersey Wakefield , Greyhound.
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