The Destructive Tomato hornworm
Big Ugly andFascinating

tomato hornworm

They are easily the biggest bug in the garden. The Tomato hornworm Manduca quinquemaculata can be 3" - 4" (10cm) long and as fat as your thumb. Because their colouring is such good camouflage they can really surprise you when you see them. You know they are there because your tomato plants are being eaten at amazing rate. That makes you search for them and they are frequently right in front of you but well disguised. Luckily they don’t appear in droves and you may only have to find one or two. The Tobacco Horn Worm also feasts on our tomatoes and is very similar in appearance. Only the amateur entomologists among us will really care who is destroying our plants.

What Do I Do With Them?
Even the least squeamish bug killer amongst us doesn’t really want to pick up one of these and squish them. Because they are so few in number they are quite easy to control. You can just shake them off the plant or cut off the leaf they are working on. Catch them in a bucket and then you have a choice. If you cut the leaf off, then use the same pruners to cut them in half and leave them on the garden pathway. The birds will quickly dispose of them and thank you for the treat. I rarely see them in my city garden and when they showed up in my country garden I found it easy just to kill them with a pellet gun and let the birds finish the cleanup.

sphinx moth, tomato honworm Where Do They Come From?
The adult Tomato Hornworm, is the large and rather god looking Sphinx Moth that we see flying on summer evenings. It’s hard to accept that these rather handsome and large, (up to 6", 15cm) moths can have such a destructive earlier stage. These adults emerge from the pupa in the soil, mate and lay their eggs on the branches and leaves of the Tomato plant. There can be two generations a year and they overwinter as pupa in the soil.

Do They Have Enemies
Yes there is a wasp that parasitizes them. If you see one with several white growths on its back, leave it alone so that these wasp pupa can hatch and attack more horn worms.

Big destructive and ugly but kind of interesting; Tomato hornworms make great science projects for the kids.

Get answers to your gardening questions by subscribing to
Ken’s free newsletter, Dallying In The Dirt

return from Tomato Hornworm to Bugs main page