The other day in the garden was a beautiful day! The sky was clear, the birds were chirping, I could hear the owls hooting in the background, it was nice and warm. The perfect day to spend some time in the garden.
I hadn’t watered the garden in a while, so I started on the carrots. As I moved along the garden, through the zucchini and squash, kohlrabi and peas, beets and celery, I turned towards the potatoes. What I saw next almost knocked me over!
Tomato Hornworm Caterpillar
It was thick! It was green! It was stripy! It had a sharp blue horn on one end! It was a Tomato Hornworm Caterpillar! AWCK! I almost fell over in surprise! I’d heard the nightmare stories about these creatures, but I’d never really experienced one in person. This one was four inches long and about half an inch thick! It was huge and it was eating my potato plant!
Earlier that day, I noticed half the potato bed had died back and turned yellow, but I hadn’t thought anything of it. I just figured that the potatoes were due for harvesting. So this tomato hornworm really surprised me. My next thought was, “how many more are there??”
Potato bed – I thought it was ready for harvesting, then I took a closer look and found 5 more Tomato Hornworm Caterpillars!
I ripped off the first branch, with tomato hornworm in tow. There was no way I was touching it! I decided to bring this creepy crawly to the chickens. I was sure they would attack it! However, only Joanne chicken responded.
First tomato hornworm found and branch ripped off potato plant! About to take this caterpillar to the chickens.
I then headed back to the garden and proceeded to look for more. Grabbing a basket, I looked over the dying side of the potato bed. I quickly found five more large sized tomato hornworm caterpillars! My skin was crawling at this point, even my hair was standing on end!
At this point, my daughter Georgia joined me in the garden and used her eagles eye to scan over the tomato beds. Together we collected four more stems with medium to large-sized tomato hornworm caterpillars. I was done at this point. That was 10 tomato hornworms in less than an hour and I couldn’t stomach anymore.
Basket is ready to take to the chickens! This batch of hornworm caterpillars are larger and heavier.
The second time around, the chickens were not as interested in this gift. Typically, chickens will fight each other for any bug or wormy creature. They are excellent predators and dig and scratch the ground regularly looking for insects. So, I was surprised to see them uninterested. I had to work to get their attention. Eventually, after no response from the chickens, my shoe had to finish them off.
“Attila the Hen” looking at me and saying, “No, thanks!”
Upon returning to the garden, I found two more tomato hornworm caterpillars in the grape vine. What this told me was that there are tomato hornworm caterpillars all over the garden, and I need to be vigilant daily at inspecting all the tomato, potato and other solanaceous plants for any sign of more tomato hornworms.
What are Tomato Hornworm caterpillars?
The tomato hornworm caterpillar is the larva of the Five-Spotted Hawk Moth. The largest moth in the garden! This moth has a two generation life cycle in one season. In the spring, moths emerge from overwintered locations in the soil. Female moths mate and deposit their eggs singly, on the lower and upper leaf surfaces of different plants. After two days, these eggs hatch and baby caterpillars begin to feed on the plant foliage. The larger they get, the more vigorously they eat. As they grow, they develop eight, white ‘v-shaped’ markings on each side of their body. These markings assist them in camouflaging into the tomato foliage. They also develop a spike or “horn” on the tail end. For tomato hornworm caterpillars, this horn is dark blue in colour.
A younger and smaller Tomato Hornworm Caterpillar.
Within 3 to 4 weeks, the caterpillar will have reached its full size of four inches and will drop off the plant and burrow into the soil to pupate. Two weeks later, moths emerge from the soil and begin their second generation. This is typically around mid-summer. By early fall, caterpillars are fully grown and will pupate in the soil until the following spring.
What to look for on your plants?
I have been battling hornworms for close to a week now. Here’s what I look for to help me spot them.
Tomato Hornworm Caterpillar poo on the leaves.
- Caterpillar poo on the plant leaves and soil below. The poo is a small dark green or black chunk, a few millimetres in size. As the caterpillar grows, their poo grows with them and becomes wider and longer.
- If you listen carefully, you can hear a faint clicking sound. I noticed this noise with the first caterpillar I picked off. It was chewing on the leaf as I was making my way to the chicken coop. It’s very faint, but if you hear it you will know there are hornworms on your plant.
- Hornworm caterpillars dislike the sun and heat of the day and will typically hide on the lower leaves of the plant. I have found it easier to spot them in the early evening when they emerge to the upper parts of the plant. However if you can’t wait (and I can’t and want them off ASAP!) look a little lower into the plant and on the underside of the leaves.
- Look for signs of destruction. It’s harder to find damage when the caterpillars are small. However, once they get big and fat, they will have chewed off the tops of the plant. Look for plant damage and you will know there are hornworms living on that plant.
If you follow these steps and in this order, starting with trails of poo, you will have a better chance of finding them.
What do Hornworm caterpillars eat?
Tomato hornworms prefer tomatoes and other solanaceous plants, such as potatoes, eggplants, peppers and deadly nightshade. However, I found two on my grape vine and read that they may even eat collard greens.
How to get rid of them?
The first line of defence is to be vigilant with daily scanning of your garden. Once tomato hornworms are present, they take work to get rid of. I have a large tomato patch of 50 plants, in different parts of the garden. I have found them throughout, as well as in the potatoes and grape vine. I try to scan all these plants daily, as well as keep an eye on other plants in the garden.
Tomato Hornworm Caterpillar poo on the plastic mulch beneath the tomato plants.
If you do find them, here’s what you can do with them:
- Remove hornworms from leaves, or cut the leaf off with the hornworm.
- Either step on the hornworm, cut it in half or feed it to your chickens.
However, if you find a hornworm caterpillar with white eggs on its back, leave it alone. These are the eggs of the Braconid wasp. The larva that hatch from these eggs will feed on the inside of the hornworm caterpillar, until they are ready to pupate. These wasps are beneficial for the garden and will seek out and feed on other hornworms. So far, none of the hornworm caterpillars I have found, have any of these eggs on their backs.
I hope this information helps you in your garden. Leave me a comment if you have tomato hornworm caterpillars now, or have had them in the past. What have you done to get rid of them?
Good luck and happy gardening!