Hornworms are here!

NBM81(Zone 5b (Denver/Boulder))July 26, 2014

Hey All!

Just a reminder to really start looking for these guys! I had a few tiny ones two weeks ago, but picked them off and then doused the plants with bt that evening. Didn't see another one until 3 days ago, so I sprayed again. I've seen two hawk moths, which are INSANELY beautiful, but that put me into ultra-high hunting mode. Plants are thriving so far, but a coworker's friend had two of her plants completely stripped and 6 others very heavily damaged overnight by 14 worms. She is in Littleton.

Be diligent! Their damage is almost 100% avoidable if you check your plants daily!

Happy gardening!


This post was edited by NBM81 on Sat, Jul 26, 14 at 19:37

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ZachS. z5 Littleton, CO

I was at the garden center today and saw lots of hawk moths, definitely been a good year for bugs.

Thanks for the heads up, I am in Littleton, too but I haven't seen any yet. Course, the flea beetles haven't left a whole lot for them to eat, my tomatoes look like lace doilies.

    Bookmark   July 26, 2014 at 9:39PM
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Lisa.from.CO(5 - CO)

Agreed, thanks for the heads up! I had one very large hornworm last week but I need to be a little more diligent in my search since my plants are now huge. I had no idea they could strip a plant that quickly!

On that note, on the way to the trash with my large worm, the ruthless gang of Blue Jays I've had all summer were visiting my backyard. They're the closest thing I have to chickens, so I though they might enjoy a snack. I tossed them the hornworm (maybe this was a stupid thing to do, but funny at the time) and when I came back not more than two minutes later the worm and Blue Jays were gone.

I hope it's not back on my tomato plant as i'm typing this! ;-)

    Bookmark   July 29, 2014 at 12:14AM
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NBM81(Zone 5b (Denver/Boulder))

I've heard birds absolutely love the things. I have some nesting in the eaves of the house right above the garden, but I'm leary about inviting them to snoop around the plants.. I'm afraid they may partake in the worms and then the fruit. Maybe they're already doing worm patrol when I'm not looking because, save for a few tiny worms, I have had no issues at all (knock on wood). Of course, I've also sprayed with bt.

One hornworm is unlikely to strip an entire plant overnight, but several can do so quite easily. The coworker's friend only "found" 14 worms.. it's entirely possible there were more. The stripped plants won't survive but the ones she caught early enough should recover.

An interesting thing - a friend who's been gardening for many years always has worms start at the bottom of his plants, but others I talk to say they notice damage near the top first. I've also read many articles that say the most obvious damage usually occurs at the top and works its way down - maybe just because the foliage is typically thinner and more visible? I was seeing very minor leaf damage toward the bottom, as well, when I found the tiny ones a few weeks ago. In the end, I guess it's all about where the egg(s) is/are laid and where the caterpillars begin feeding. :)

    Bookmark   July 29, 2014 at 9:20AM
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mstywoods(z5, Westminster, CO)

Is this the worm you are talking about?

Colordo State site has into on them (which is where I got the pic above):
Tomato/Tobacco Hornworm.

I'll keep an eye out for them - thanks for the warning!!

    Bookmark   July 29, 2014 at 7:26PM
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ZachS. z5 Littleton, CO

That's the one!

I have never had a destructive infestation of hornworms myself, I have only ever found one or two per season, so I guess I've been lucky. Likely there isn't enough preferred food sources for the moths around here so they don't come around often (what flowers do they like best anyways?)Course you all are going to run me out of town with pitchforks and torches when I tell you that when I do find them I put them in little "houses" raise them into adult moths with my son as a little science experiment.

    Bookmark   July 29, 2014 at 7:36PM
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NBM81(Zone 5b (Denver/Boulder))

That's them, mstywoods! It's funny that almost everyone has seen them in their garden a time or two, but it seems only a few people really get nailed by them.

Always pays to be diligent. :)

    Bookmark   July 29, 2014 at 8:25PM
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I've never had a hornworm infestation, either, and I haven't encountered diseases on my tomatoes. I think it's because I use homemade, plant-based compost in the soil. Compost seems to increase a plant's immunity to diseases and pests.

    Bookmark   July 30, 2014 at 8:28PM
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ZachS. z5 Littleton, CO

I have found, in general, Colorado has fewer pest and disease problems than many other places. I rarely see anything at "infestation" levels and the only disease that has ever totally ruined a crop for me is powdery mildew on my squash.

    Bookmark   July 30, 2014 at 10:04PM
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davids10 z7a nv.

my cats love hawk moths which seems to take care of the hornworm problem

    Bookmark   July 30, 2014 at 11:52PM
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mayberrygardener(z5a, Broomfield, CO)

I had never heard them called hawk moths before (sphinx moth is what we call them), but now I know that the hornworm is the young, I might not be so fond to allow them to visit nightly in the springtime and sip from our petunias. We had a pair that visited the flower bowl on our patio table every night for a few weeks after the spring swap, but we have yet to see any evidence of worms. I'll definitely keep an eye out for them, and any findings will go to the greedy chickens! Turn those worms into eggs... YUM

    Bookmark   July 31, 2014 at 10:14AM
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ZachS. z5 Littleton, CO

It is both, I think. If you get tomato hornworms, it grows into a "5 spotted hawk moth" if you get tobacco hornworms, it grows into a "Carolina sphinx month." Not sure which ones are more common in Colorado, as I never paid close enough attention. I think last year, the one I found was a tobacco hornworm.

    Bookmark   July 31, 2014 at 11:12AM
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bugdoctor(5 CO)

In academia we call them Sphingids, for their family Sphingidae. However, growing up here in Colorado we called them sphinx moths. That's what is so tough about common names.

There is a white-lined sphinx moth that is also in the family Sphingidae. They are having a stellar year and are in abundance. One of the few moths that are diurnal, or nectar during the day. Perhaps this is what folks were seeing in the spring. People often mistaken them for hummingbirds as they hover and feed on flowers.

Here is a link that might be useful: Tobacco/Tomato hornworms

    Bookmark   July 31, 2014 at 10:51PM
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I like to hook up tiny chariots made from bottle caps, tooth picks, and thread and hold hornworm races.

/make some good money as the bookie

    Bookmark   August 2, 2014 at 3:47PM
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westy1941(Boulder County, CO)

OMG I've never seen such big fat ones! This is my first summer gardening here (Erie). I had them on my tomatoes in Illinois and Ohio too but never this big! A few were four inches long and at least 1/2 inch thick I noticed them yesterday and waited til DH got home because I can't stomach picking them off. He dropped them into soapy water.. ICK! The soil here is like cement because I didn't have time to amend but will be doing a lot with this tomato garden in the Fall to prevent these from returning next year.

    Bookmark   August 5, 2014 at 2:35AM
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