Saturday, July 31, 2010

Hornworms: Where is a parasitic wasp when you need one?

I knew they were there even though I couldn’t see them just yet. I could however see the damage they left behind:




I’ve been finding a few small hornworms on tomatoes in another part of the garden, so I knew one had to be in there somewhere. I searched among the foliage for him carefully. It took a while to spot him, then almost as an optical illusion he appeared on the stem he was perched on all along:


It was almost like drinking a magic potion that gave me special abilities to see invisible things, because just then another one appeared on a leaf near the first one. “Ah, two!” I thought as I ran inside to get a fresh jar of soapy water and the camera.


As I scooted down on one knee to focus the camera on the hornworms, I was alarmed to see two more!! There were four very large hornworms on one tomato plant!


Now these guys creep me out, so after taking a few hurried pictures, I donned a glove and reached in, snatched them off the plant, and quickly dropped them into the jar of soapy water.

I’ve been watching my tomatoes carefully for signs of disease and have found and killed quite a few small hornworms over the last few weeks. I don’t recall ever having such a population. Curious about their lifecycle, I did some research and was surprised to learn that their eggs hatch in only 3-5 days. Also, the ones in my garden are tobacco hornworms, not the expected tomato hornworms. The difference is in the horn color and markings on the body. Tobacco hornworms are usually green with seven diagonal white lines on the sides and a curved red horn. Tomato hornworms have eight V-shaped marks on each side and their horn is straighter and blue-black in color. Both feed on the foliage of various plants from the Solanaceae family.

The eggs can be found on the underside of leaves and sometimes even on top. They are translucent green and measure about 1 millimeter in diameter. Tobacco hornworm life spans over 30 to 50 days. The eggs hatch into green larvae which can grow to 70 millimeters long. The larvae become the tobacco hornworm pupa that finally matures into the adult Sphinx moths or hawk moths.

A new task has been added to my evening routine. Now armed with gloves and a large jar of soapy water, I hunt hornworms to keep my tomatoes safe.

14 comments:

  1. Uh, I hate those buggers. I can't even manage to get them with gloves, I just break the whole stem off and smoosh em!

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  2. Those things are straight from the black lagoon. There's no excuse for them. THey're just horrifying.

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  3. Oooh, so camouflaged! It's hard to see it!

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  4. Oh those look just like the ones that were in my garden last year. I had a real invasion. This year there is no sign of them yet. Usually I see the foliage or tomato damage before I see any hornworms.

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  5. Shawn Ann: Smoosh em! Oh my, I don’t even want to think about the mess that would leave.

    Ribbit: I agree, they are horrifying! They totally gross me out!

    Meemsynyc: It was really strange to realize that they were right where I was looking but I couldn’t see them.

    Daphne: I have never had so many in my garden before. I too usually see the damage or the poo first then seek out the hornworm.

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  6. They sure are hard to find, but it's easy to locate the eggs before they hatch. I've found probably 50 so far - and no hornworms...

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  7. I have yet to have horn worms since we moved from central Washington to our current location. Going on six years in this house and garden and still none. I likely just jinxed myself by admitting that! I have chickens now so if I did have them invade, they would be instant chicken feed! We used to get them alot when I gardened in central Washington state. They always creeped me out but it never stopped me from donning some gloves and plucking them off.

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  8. EG: I wish I spotted the eggs before they hatched. It's much too late now, so I'll have to search them out.

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  9. kitsapFG: I have gone many years of gardening without ever seeing horn worms. I am not thrilled to find them now. They really creep me out. I am sure the chickens would love these.

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  10. I haven't yet seen them here. Your description of the "now you see 'em" magical thing is so spot-on. They sure can eat a lot in not a lot of time. I wonder if my chickens would like them?

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  11. These worms are tricky. You finally find one and more picture taking, leads to finding 3,4,5,6 ... or more!

    They have gotten on my outdoor tomato plants, but I havent had any problems inside of my outdoor greenhouse. It's not 100% enclosed from the outside environment, so bugs do occasionally come and visit my plants.

    Someone has mentioned the use of BT as an organic way to take care of the worms. I will have to try this soon :)

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  12. Ugh! Yuck! I'm coming back to your post after reading it the other day, because guess what *I* found tonight?!?! Argh! I'm pro smooshing or stepping on bugs, but not these bad boys... Soapy water's the only way to go!

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  13. Unfortunately, I just found about 15 of these bloaks feasting away on my anaheim pepper plant and a few nibbles out of one of my tomatoes here in Raleigh. These are tobacco hornworms, but I also found a few caterpillars of a different breed hiding in the weeds one minute and then being eaten by ants the next! I cannot seem to find the eggs of these big feeders, but a few of them have been scourged with wasp larvae... I only wish I had some of those chickens!

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  14. You actually should let them live. You'll never get the parasitic wasps in your garden if you keep killing their hosts. I finally made peace with them several years ago and let them all live, I now notice that their numbers are fewer and fewer and the birds eat them and the wasps get them. The truth is the tomatoes can live without leaves and the worms usually only eat a few tomatoes.

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