By: Chiot's Run
When I first started growing tomatoes I used to pick off the tomato or tobacco hornworms and squish them with a rock. Then one year I missed one and spotted it with the tiny white eggs from a parasitic wasp on it's back. Ever since then I've made peace with the hornworms in my garden. I never pick them off or do anything to get rid of them. They get to eat some tomatoes leaves and a tomato here and there in complete peace. Why the change of heart? I don't want to get rid of them and risk the parasitic wasp not having a host for it's eggs. I also don't want the birds to go hungry, as they seem to find these giant juicy worms a complete breakfast. The truth is they're not that damaging to tomato plants and I can plant extra plants just for them. Perhaps a little defoliation is good for tomatoes this time of year and I don't mind losing a couple tomatoes, I have plenty to go around. The truth is that often when we step in we upset the balance of nature and make our problems worse down the line. If we squish or kill all the hornworms we'll never have the braconid wasps in our gardens. Without the wasps we'll end up with more hornworms, aphids and other insects. We may also inadvertently kill a hornworm that has already been parasitized by a wasp since it takes a few days before the white worms appear on their backs. I'm convinced that I'm encouraging biodiversity in my garden by making peace with hornworms and other things viewed as "pests". I have noticed that the less I interfere with nature the more balanced things become, even in my small quarter acre garden. I encourage you to let the hornworms and other pests live and see how everything balances out in a few years!
Do you have any pests that you've made peace with?
Here's an interesting article from the BBC about how plants can send out SOS signals to predatory insects when they sense they're being attacked by caterpillars & other insects. And the specifically studies hornworms.