What to do about the hornworms?

I found two more hornworms on my tomato plants today. For those who may not know what a horn worm is, it is a caterpillar that loves to eat the leaves and/or the fruit on your tomato plants. They are nearly impossible to avoid. Or at least that has been my experience. There are several ways to control them, the least pleasant of which is to pick them off by hand. Now being a guy, and having a rep to live up to, I hate to admit this but for what it's worth, I find picking squishy caterpillars off of my tomatoes to be repulsive. Especially when if you squeeze a horn worm the wrong way it excretes a fluid on you. Add to that the fact that I am colorblind (which makes finding these well camouflaged creatures very difficult) and you can see that even though this is the least invasive/disruptive manner to fight them off, I am not a fan of this method. The horned worm will typically be found on the undersides of the stems and leaves of your plants, and when you see one, you will immediately know why they are called horn worms. The horn is on the posterior end of the creature and is not harmful.
 My preferred method of dealing with hornworms is with an organic method. By spraying with BT (Bacillus thuringiensis) you introduce a bacteria that attacks the stomach of the caterpillars. But there is a debate as to wether even this is a smart environmentally friendly method. I will leave that debate to others, but I use this stuff and it works and you can eat the fruit the same day you spray it on. This bacteria is not harmful to humans so far as anything I have read. There are many different strains of BT so be sure to read the label directions (as you should when using any product) and get the strain that is right for you.
Most seasons, however, hornworms are kept at what some folks consider acceptable levels by a wasp parasite. Parasitized hornworms are easily recognized by the small white oblong cocoons attached to their backs. Such worms should be left in the garden so the emerging wasps can parasitize other hornworms. I usually pick caterpillars which have the cocoons on them off my plants ( I can't deal with the damage they do), but rather than stomp on them I take them a good distance from the garden and release them. This way the wasps hatch and kill the caterpillar and then live on to help me fight them off next year.

 Another method is using chemicals. I do not use this method so you should contact your local agricultural extension agent for products approved for use in your area.


If I didn't say it somewhere in that lengthy post (sorry) I will be spraying BT on my plants tomorrow morning.