Tomato Hornworms – finding them with UV light at night


I read that you can see tomato hornworms with a UV (ultraviolet) light. Two nights ago we went out to see if we could spot them. I had gotten a UV flashlight last year but didn’t receive it till after the first freeze so there wasn’t much to see. But not that night!  In the daylight I could only see the chewed up leaves on 2 plants but could not find the hornworms. But at night they are easy to spot with the UV light. We found many small ones as well as big ones that we would have missed if not for the UV light.


Also we noticed that there seem to be either fluorescent bite marks or trails where they had been so if we saw these we would see if any were hiding. We probably got 30 tomato hornworms in all. What a great way to find them.

8 comments on “Tomato Hornworms – finding them with UV light at night

  1. gene solyntjes says:

    Hello Jannine,
    Exactly how do these hornworms affect your tomato crop?


    • They defoliate the branches of leaves and can wipe out the plant in a few days. I also saw the other night that they had eaten part of the tomatoes. they’re easy to control-just hand pick and now with a UV light, the job just got easier.


  2. Jenn B says:

    This is awesome! Very Alice and Wonderland-ish.


  3. thegardenrn says:

    Hello. This is a great photo. I was wondering if I could use it for a future talk that I am having with the Southeast Master Gardeners of Wisconsin? I also have a blog


  4. […] can also use a black light to find hornworms, after dark. This works really […]


  5. Harold says:

    Great reading yourr blog


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