Monday Morning Gardening: Hornworms

Tomato season is in full swing here in Southern California.   Growing tomatoes has become so popular that it is hard to go into a nursery center or a big box store without seeing rows and rows of tomato plants just waiting for you to  take them home. One day you are out looking at your plants, only to discover that the leaves appear to be eaten and if you have tomatoes that are ripe or almost ripe, they are being destroyed.  You don’t see anything on the plants, but look closer and be very still and you might find a dreaded Hornworm (Manduca spp), which are the larval stage of the Hornworm moth.   Most people run for their houses, when coming face to face with these creatures of the garden, but be brave!  You are the best defense against these tomato pests.

What to do?  The most effective way to deal with these pests, is to be vigilant in your inspection of your plants and if you find the worms, remove and destroy them.  Not able to see them?  Use a light spray of water (neither the worms nor your tomatoes like to be wet, so using a LIGHT spray is imperative) and watch for movement.  The worms will attempt to get away from the water and that’s when you can grab them.

If your plants are showing signs of having a heavy infestation, you can apply Bacillus thuringiensis (Bt) to the leaves of the plants.  It is a microbial insecticide and only effects the hornworm, so it is safe to use on your tomato plants.  Most home gardeners find the “seek and destroy” method effective for the management of these worms.

Remember, one of the joys of having a garden is being outside and enjoying your plants and the growing process.  Keeping a good eye on your plants and catching things like an attack of Hornworms should be easy if you are spending time in your garden.  Whether it is containers on a balcony, a raised bed on your patio or a backyard converted into a veggie garden, get out and enjoy it!  It will come alive with your attention.


About the Author

Laurie Menosky has been in the UCCE Master Gardener program since 2007.  During this time she has taken her love of gardening from a level of modest interest to an all out passion. She has enjoyed learning more about growing edibles in the past few years, even though our ocean-side living often proves to be a challenge.  She enjoys working with other volunteers to help people understand simple and confident ways to incorporate gardening into even the smallest spaces.  Bringing a love of gardening to children is also so important and Laurie is proud that her grandchildren are enthusiastic gardeners.