Cornmeal and the Exploding Hornworm Experiment

As I mentioned in yesterday’s post, another hornworm stopped by to pay our plants a visit. The tomato plant is in very sad shape. It has been passed over by most everything that’s come along lately, with the exception of a few tiny spiders who have spun their webs along its dusty branches.

Waiting to see what new pest or pestilence afflicts the plant has become something of a hobby. I leave it be strictly for its educational value. No sense digging it up and tossing it if I might learn something that will be helpful for next year’s crop.

Our latest hornworm visitor did not inflict much damage to the bell pepper plant. I must have caught it relatively early. The plant will survive. But what about the worm?

Over a week ago I tried cornstarch as a home remedy to rid garden plants of hornworms. It appears to have worked on the tomato. Nothing has snacked on it recently, as far as we can tell. The plant was in rough shape by the time I bathed it in cornstarch. But the top few branches looked promising, and it has not been disturbed since.

The cornstarch stuck very well to the tomato plant’s almost hairy leaves and stems. The bell pepper, by contrast, has much smoother leaves. The starch stayed on them for only a day or so. I was negligent in reapplying it; thus our latest diner had a free meal at our expense. Since I needed to reapply something, and had captured the culprit red-handed, I thought I’d test out a second home remedy.

My friend Susan and I were intrigued by reports of self-rising cornmeal or flour causing hornworms to burst. Supposedly the worms eat the self-rising meal, which has been sprinkled liberally on and around the plant you’d like to protect. The meal is activated by the water in the worms’ stomachs, causing them to swell and burst.  The word “explode” was used in more than one description.

I was quite skeptical of this home remedy for several reasons. First and foremost I spent over an hour scouring the internet for a picture of hornworm death by cornmeal and found absolutely zero, zilch, nada. If something explodes, ruptures, oozes, or can be enticed to do so, the evidence is all over the world wide web in two shakes of a lamb’s tail.

Second reason I am skeptical is because of where hornworms like to hang out — namely on the underside of leaves. Meal and flour may stick to the top sides, but it is nearly impossible to apply to the bottom. I doubt caterpillars and their kin ingest as much meal as one would think, especially if they’re not crawling in it. Their movements up and down the stems should be enough to knock at least some of it to the ground.

But there was really no way to know what the outcome would be without giving this new remedy a try. The hornworm was placed in a small plastic coffee can along with the remainder of the leaf it was eating.  I sprinkled self-rising cornmeal liberally into the bottom of the can, got Sam’s help securing a piece of screen over the top, and waited.

Hornworm in cornmeal

This morning the leaf was gone, eaten except for the stem end. I expected to see a dead hornworm. To my surprise, the worm was not dead. Aside from being quite dusty, it appeared to be no worse for the wear.  Here is link to a very short video of Mr. Hornworm searching for a way out of the can: Hornworm in cornmeal.

So what did I learn from this little experiment?

  1. Hornworms are excellent possums. They can play dead very convincingly, and at the drop of a hat, too. The worm didn’t move much at all as I plucked him and his leaf off the plant and placed them in the can. As soon as I dropped the meal in with him, the worm froze completely. It remained rigid and completely still for a very long time — hours and hours. Honestly I thought it must have suffocated. I wrote this off as a failure and pondered what I’d do differently the next time a hornworm came along. Imagine my surprise this morning!
  2. Some sources will tell you that it’s “rare” for hornworms to eat plants other than tomatoes. Bell pepper was one of those lumped into the “rare” category. Don’t you believe it!
  3. Any success from sprinkling flour or corn products probably has a great deal to do with where the meal, flour, or starch is applied. If the worms detest the stuff, it would have to be on texture alone as it does not appear to actually cause them harm.  Perhaps they would pass a plant by if it were simply surrounded by a circle of gritty material.
  4. Droppings left by hungry worms show up well in the light colored dust under the leaves, even if the dust has been there awhile. So you get a bit of help spotting new intruders.

Whew! That’s a lot of learning for a day and a half.

I dusted the plants again, this time with cornmeal, just to see what happens. The cornmeal was less successful at sticking than the cornstarch.  No surprise there. Cornmeal dusting

Expectations have been adjusted to fall in line with the results of this first gardening experiment. No longer do I anticipate exploded hornworm carcasses all over the vegetables. But, there’s always something new to try. Rumor has it beer repels slugs, and something called seed tape can be made with toilet paper. Hmmm… I see a trip to the grocery store in my future, just as soon as I wrangle up some slugs and a bottle opener.

© 2015-2016 Our Lives in Stories



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