Monday, June 30, 2014

Tomato Hornworms

What are Tomato Hornworms?

One day you are looking at healthy tomato plants, the next morning they’ve been disseminated to a mere collection of leafless stems. You search your tomato plant only to find a caterpillar that, if photographed at point-blank range, resembles something from an old Godzilla movie.
You have just been invaded by Tomato Hornworms, a green caterpillar that has a voracious appetite, making short work of your tomatoes (potatoes, peppers, and eggplant), and grows to be five inches long and about as big around as your thumb.

These giant caterpillars are the larvae of hawk or sphinx moths.  Once they get enough to eat, the worms drops to the ground and burrows down a few inches to where the cycle begins again.
The first indication that you’ve been invaded is when the leaves of the plants come up missing, often those located at the tips of the branches.  By following the trail of frass, or caterpillar excrement, you can find them camouflaging themselves along a leaf vein or stem.  The large the hornworm, the more damage it will create on your tomatoes.

How to get rid of Tomato Hornworms
** Tilling – Although there isn’t much to do if you are just now experiencing the infestation, you can contain them for the upcoming years by tilling your soil right after you pull the tomato plants in the fall and again in the spring.  This process has a 90% mortality rate.

** Handpicking – Okay I have to admit, I call my husband in for this one.  Although they will not hurt you the bugs give me the willies.  Still, this tactic is still the best control if you have time and a small garden.  Be methodical in your search, looking at the stems as well as the underside of the leaves.  To kill the offending worms, drop them into soapy water.  To make finding them easier, spray the plants with water will increase the visual contrast.
** Wasps – Wasps feed on the hornworms and are a natural control.  If you find a hornworm with what looks like grains of rice on its back, don’t get rid of those.  That is wasp larvae and it will do more to eliminate your problem than any solution here.

** Bt - You can use a botanical remedy called Bt (Bacillus Thuringiensis), which is a bacterium that acts as a stomach poison to the caterpillar.  It doesn’t hurt the plant or Fido, but it does affect other insects, insects you may want to keep.
** Homemade Insecticides – Try making a brew of 1 cup vegetable oil, 1.5 cups of water, and 2 teaspoons dish soap.  (You can add cayenne pepper or steep in a few chili peppers to add to its potency.)  Spray directly on the leaves and vines of the tomato plant.

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