Yes, it's sold under various brand names. Every garden center sells at least one.

If you ask for a "natural" or "organic" caterpillar killer, the personnel may know what you want. If not, you'll have to read labels. Typically, the ingredients list on the label includes both the abbreviation Bt and the full name, Bacillus thuringiensis.

My experience at all of the big box stores is that the salespersons will have no idea what BT is much less what the product name is. There are a number of Bacillus thuringiensis products out there but which one to use depends on which insect problem you have. Dipel, Thuricide, BioBit, Steward, and Best Buy are brands of BT-K I am aware of and there may be more. Vectobac, Mosquito Dunks, Gnatrol, Bactimos are brand names of BT-I, and Trident, M-One, M-Trak, Foil, Novodor are brand names of BT-SD.
I have not yet seen any of these products on the shelves at any of the big box stores, and the sales people at these stores try very hard to steer me to other, much more poisonous products. Every one of our locally owned garden shops has these products on the shelves, although again the sales people will often try to sell me some other, broad spectrum poison I don't want.
You do need to be careful even at your local garden shop since one of ours, several years ago, sold a gardener a Bayer pesticide to treat frost damage.

caroline, what is the insect that you are hoping to control with a Bt product?

hornworms, and possibly a few other maggots.
Thanks for the info. Yeah, I've asked about it and these folks are clueless.

Bt is effective against hornworms and other caterpillars only if they are less than half-grown. Any older than that can be dealt with on a one-to-one basis. That is, search and destroy on a regular basis.

Bt doesn't work for maggot (baby flies).

I just bought some at home depot. It's called Thuricide.

Thanks SuzyQk - that's what I needed to know!! :-)

BUT, can you at least catch the babies and young ones with bt? Stop the breeding, at least?

Read the label on the package of Bt. There is more than just one strain. Bt-K (kurstaki) controls the young, actively feeding larvae of moths and butterflies ONLY. These are commonly known as caterpillars.

Bt-I (Israelensis) can control the larvae of insects in the Diptera order, such as flies, mosquitoes, gnats, and their kin.

There are also strains that help control certain beetle larvae, etc.

Both are packaged by dozens of different companies and are available under many brand names. READ THE LABEL. I've also been able to find these products in big box stores all over the place, for many years.

midsummer, did that answer your question on this 2 year old thread? If not, you may want to post your very own thread and bring the subject up once again. It's a good topic.