I've been checking my tomato plants almost daily to see how they're progressing (lots of baby tomatoes!) and also to check for signs of diseases and pests. This week I found my first tomato hornworm caterpiillar.
Well, to be truthful, I found the frass first. Frass, you ask? Well, it's just a fancy word for caterpillar poop. It's usually easy to spot because it's dark and stands out strongly against the leaves, unlike the caterpillars themselves which tend to blend in. For a close-up of the frass, click here.
I scoured the tomato bushes and found four young caterpillars and quickly introduced them to the bottom of my shoe. This is the first line of defense (pick and squash) if you're using integrated pest management. My next step was going to be treating the plants with Bacillus thuringiensis, a microbial insecticide, but I was unable to purchase it at my local big box store during last night's late shopping trip. Darn those big box stores.
My tomatoes have shown other signs of pest damage, namely leaf miners, but I haven't treated them because leaf miners usually don't cause major problems. Tomato hornworms, on the other hand, have voracious appetities. No way I'm leaving those buggers on my prized tomatoes.
Update 6/21/08: it looks like I misidentified this caterpillar. It's actually a tobacco hornworm (Manduca sexta) and not a tomato hornworm (Manduca quinquemaculata). Tomato hornworms have eight white V-shaped markings on their side while tobacco hornworms have seven diagonal white lines.