Tomato Hornworm Moths at Grand Canyon National Park

Tomato Hornworm Moths at Grand Canyon National Park

Tomato Hornworm Moth in flight to Moonflower - Grand Canyon National Park - Arizona

After a full day of activity at Grand Canyon National Park, Bob and I were returning late to our room at Maswik Lodge when a flicker of movement drew my eye towards the stunning night-blooming Moonflowers.  We were not the only ones attracted by the glowing white flowers.  Numerous Tomato Hornworm Moths (Manduca quinquemaculata), also known as Five-spotted Hawkmoths,  were circling for a landing.

Tomato Hornworm Moths at night in Arizona

I was really intrigued by these nocturnal cousins of butterflies because they seemed to hover helicopter-style like small hummingbirds, which is why they are also known as Hummingbird Moths.

Moonflower plant during daytime - Grand Canyon National Park - Arizona

We had actually taken notice, early that morning, of the striking white blooms on the Moonflower plant, otherwise known as Datura wrightii.  The large, trumpet-shaped corollas are usually withered by midday, having opened the evening before just as darkness cloaks the land, but we were up bright and early before the blooms wrapped into themselves.

Moonflower during daytime with bugs - Grand Canyon National Park - Arizona

Moonflower, or Datura Wrightii, is a native perennial wildflower in Arizona, and grows well in either a desert or upland environment.  The plant is highly toxic and, if improperly handled, can be lethal.  Since before recorded history, the narcotic qualities of the plant extracts have been known, and they once figured prominently in native religious ceremonies because of their hallucinogenic qualities.  Hence, another name for the plant is Sacred Datura or Sacred Thornapple.

bees on Moonflower - Grand Canyon National Park - Arizona

The highly-fragrant blossoms attract a variety of insects during the early part of the day,

Tomato Hornworm Moths at a Moonflower - Grand Canyon National Park - Arizona

and are a magnet for night-flying moths such as the Tomato Hornworm Moth.

tomato Hornworm beside tomato

In their caterpillar stage, the Tomato Hornworm Moths are plump, marvelously well camouflaged green caterpillars that feed voraciously on tomato plants, pepper and potato plants, chowing down on the leaves until branches are left bare.  Among other plants in the Solanacaea family that the tomato hornworms favour are the Sacred Datura.

tomato hornworm caterpillar sits on leaves

Tomato Hornworm Moths get their name from the fact that the caterpillars have a horn gracing the back end of their bodies.  If a caterpillar is disturbed, it will raise its head and front third of its body into a contemplative stance and remain that way in what is referred to as a sphinx-like pose.  Hence, the moths are also called Sphinx Moths.

Tomato Hornworm Moth

It is hard to believe that the homely tomato hornworm caterpillar morphs into such a magnificent moth.  The Five-spotted Hawkmoth is recognizable by the five pairs of yellow bands on its abdomen.

Adult Tomato Hornworm Moth - Arizona

These moths have a wingspan of between 9-13.5 centimetres (3.5-5.5 inches).  Maybe that is why a lot of people find them to be creepy and scary.  Between its size , fuzzy antennae and the fact that it flies erratically at nighttime, some unsuspecting person prowling around in the dark might be spooked when one of these moths nonchalantly brushes against their skin.

Jean & Bob on edge of Grand Canyon - Arizona

For Bob and me, however, after a full day of hiking at the Grand Canyon,

Moonflower plant - flower pods - Grand Canyon National Park - Arizona

and the promise of new blooms on the Datura plant opening at sunset, judging by the large, plump buds we saw that morning,

Sunset - Grand Canyon National Park - Arizona

we were filled with anticipation when the last rays of sunshine kissed the upper reaches of the canyon walls.

Moonflower plant at nighttime - Grand Canyon National Park - Arizona

Sure enough, fresh startling white flowers had opened and awaited the attentions of the Sphinx Moths.  Sadly, we saw no sign of them the following evening.  I guessed they had moved on to greener pastures.

Tomato Hornworm Moths around a Moonflower plant - Grand Canyon National Park - Arizona

For Bob and me, the Five-Spotted Moths had made a real impression, and we eagerly passed that way every night before retiring, on the off chance that the moths would be visiting the Datura plant again.  They are magnificent insects!

Learn more about Tomato Hornworms in Ontario, Canada at:  Ontario Food and Rural Affairs

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  • What an interesting experience of getting to see those beautiful moths at night! I would like to use your photo of the tomato hornworm moths feeding at night on Datura blossoms for a presentation to our master gardeners. We are promoting native plants for pollinators, but I want to educate them about the plants needed by our nocturnal pollinators. When I was a child moths splattered the windshields of our cars after driving at night, and hundreds swirled around street lights at night. Sadly, this no longer happens here. Dr. Doug Tallamy says we are facing an insect apocalypse!

    Thanks for your consideration,
    Suzanne Hill
    Frederick County Master Gardener
    Frederick MD

    • Hi Suzanne. Thanks for reaching out to us. I, too, recall the numbers of moths and insects in general that used to coat my dad’s windshield when we were out driving at night. Sadly, that is not the case anymore. I have messaged you via email regarding the use of one of our photos.

  • Deb Daly, Bright ON Canada

    Very interesting reading about your encounter with the tomato hornworm moths at Grand Canyon National Park. I found one on my hedge last evening, took a picture and today found your article. I don’t know if they’re common around here (southwestern Ontario), but am going to look into it. Thanks for your article!

    • I’m glad you found our article of interest. Thanks for getting in touch. I do believe Tomato Hornworm Moths are somewhat common in Ontario, but then again, I am no expert when it comes to insects and such. Good luck in your searching.

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