How to Kill Hornworms on Tomato Plants
Tomato hornworms (Manduca quinquemaculata), also known as tobacco hornworms, are the larva of the five-spotted hawkmoth. The hawkmoth is a large moth, approximately 4 to 5 inches wide from wingtip to wingtip. Hornworm caterpillars are light green at first and deepen in color as they grow. They can be hard to spot because they blend so well with the stem and green fruit of the tomato plant. Does this Spark an idea?
Instructions
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Pick the worms off by hand. Take a bucket with some soapy water to the garden and pick off each worm by hand and drop them in the bucket. This is a tedious process, but it is the most organic and inexpensive way to rid your garden of the pests, according to the University of Minnesota Extension.
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Introduce parasitic wasps to your garden. Parasitic wasps (Cotesia congregatus), which can be purchased, will seek out the hornworms and lay their eggs on them, and the eggs will then feed on the worm. You will know this method works when the hornworm has a lot of small, white eggs on its back -- leave any hornworms you see in this condition in the garden, advises the University of Minnesota Extension. While this method does not necessarily work the fastest, it will give the most long-term coverage as the wasps will continue to live in your garden.
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Dust or spray your tomato plants with Bt (Bacillus thuringiensis). This bacteria is a more natural way to control hornworms than a chemical insecticide. The hornworms eat the bacteria and then die within a few days. Be sure to dust or spray all parts of the plant including the underside of leaves.
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Spray your tomato plants with pyrethrin/pyrethrum insecticide. Pyrethrin will kill any pest it comes into contact with, though, so be sure you are only spraying where there are hornworms. The Yardener website advises that making a solution of 2/3 pyrethrin and 1/3 insecticidal soap increases the effectiveness of the pyrethrin.
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Let your chickens roam the garden. Some gardeners say that letting your chickens (if you have them) roam will keep all pests down, not just the hornworms.
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Spray your plants with vegetable oil or liquid soap. Mix it with hot pepper sauce if you like. This can make the plants very unappealing to hornworms as well as to other pests in the garden.
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References
Resources
- Photo Credit green worm image by JoLin from Fotolia.com
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Comments
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Chickens also like tomatoes though. So, if you are going to let chickens roam your garden, you'd better be prepared to lose some of the tomatoes to the chickens instead of to the worms. Guineas would be a better proposition as they only eat bugs, not veggies.
