Monthly Book Giveaway - February 2023

Gardening #4: The Tomato Hornworm

Gardeners don’t like tomato hornworms on their tomatoes!

If you have ever had one of these caterpillars in your garden, you will know how destructive they can be. They are the hungriest of hungry caterpillars and are a real garden pest. 

What does a tomato hornworm look like?

The hornworm can grow to 4” in length. (That’s big, people, big!) The large caterpillars will have the markings as in the photo above, with a dark “horn” on their tail-end. 
Smaller hornworms are harder to identify because they lack the white markings, which apparently glow when a black light is shone on them. 
Tip: because they blend in with the plants and are hard to notice, go out at night and use a black light to search your plants. The tomato hornworm will glow in the dark. 

Life Cycle of the Tomato Hornworm 

  • First, they are light green eggs on the underside of leaves. 
  • When hatched, the caterpillars eat, eat, eat, and reach their full size in about 3-4 weeks. 
  • The caterpillar, then, drops to the ground, burrows in, and starts the transformation, first into a pupae. 
  • In just two weeks, a moth emerges and starts the second generation of the season. 
  • The next pupae remain in the soil for the winter and, then, the cycle continues the next year. 

What does the Tomato Hornworm Moth Look Like

This, my friend, is where life gets tricky.
What do I mean?
The tomato hornworm and the hummingbird moth are one and the same.
It is definitely a love-hate relationship here in my gardens!
The hummingbird moth, which is so unique and beautiful and fairly easy for me to photograph, is also a wonderful pollinator in the garden. It is a treasured guest. But it is a tomato hornworm … not so welcome.

What Do Tomato Hornworms eat?

Obviously, tomatoes are the caterpillars’ plant of choice. 
The garden pests will also eat potato plants, eggplants, and peppers. You can also find them on jimsomweed and other nightshade plants. 

Protecting Your Plants From the Hungry Caterpillar 

  1. Observe, observe, observe: as soon as you notice any amount of destruction, start your search and remove the caterpillars and/or the eggs from the underside of leaves.
  2. Thank the parasitic wasps. The larvae feed on the hornworm (from the inside out, by the way.) in the photo below, you can see the cocoons on the caterpillar. 
  3. Other predators include lady bugs which eat the eggs. 

And the question is

What do you do with the hummingbird moth? 
For me, it is: 
 “embrace it”. 
I let them live their life - until I find them eating my vegetable plants and, then, it is survival of the fittest. Sorry, future-hummingbird-moth, but you chose the wrong plant to eat!

Your thoughts?
- Debbie

a simpler life