is that a tobacco, or tomato, hornworm?

tobacco hornworm on nicotianaTHEY’VE ALREADY STARTED on the fall cleanup. The tobacco hornworms, or Manduca sexta, that is–who love to chomp late in the garden season here on my haze of self-sown Nicotiana, or flowering tobacco–the annuals I let spread themselves around for my visual pleasure and to attract hummingbirds. But how do I know these voracious giant green caterpillars aren’t actually their close cousins the tomato hornworms, Manduca quinquemaculata (since both species will eat Solanaceous crops such as tobacco and tomato)? It’s all in the stripes, and the “horns.”

The tomato hornworm and tobacco hornworm both have angled white markings on their sides, but the tobacco hornworm’s seven marks just go in one direction, and the white is edged in black; the tomato hornworm’s eight marks per side are each more like a chevron, or “V,” with no black edge. The other big difference: Tobacco hornworms’ “horns” (which look like a tail) are usually reddish; the tomato hornworms’ are black or blue-black. (Oddly, I don’t have a photo of the tomato hornworm, but you can compare them on this University of Florida site.)

tobacco hornworm eating nicotianaI think the one just above was more recently “hatched,” because its body was still dark-colored, but I’m not certain. Maybe he’d just been smoking and got all sooty? (Kidding.) You can see all the life phases–caterpillar, chrysalis, sphinx moth–here.

I have to say, I’m violent when one of these guys is eating my tomatoes in early summer, and it’s all “off with their heads” over here then. But right now, as the garden unwinds anyhow? Eat all you want; the buffet is open. Go ahead and get fat and juicy, tobacco hornworms–and maybe some bird will eat you!

13 comments
September 12, 2012

comments

  1. Heidi says

    Usually I break off the stem and give them to my chickens, but the other day I saw one of those hornworms (not sure which one!) on my tomatoes that was covered with what looked like grains of rice – the larva of a parasitic wasp. So I let them do their thing!

  2. narf7 says

    What pretty “worms”! We don’t have native (or any kind) of tobacco here in Australia (although an old Hippy American man that we know down the road seems to have some growing on his property…) so the hornworms would be severely hungry and with our short growing period in Summer (we are in Tasmania Australia), the tomato hornworms would have problems as well. Aside from the slugs that come out in force when we lock the duck up in her coop for the night, we don’t have too many problems with grubs, worms etc. here as the chooks are free range and deal with most of them. I might just have to get that lazy duck out on a string at night to deal with all of those slugs! (Or get out there and collect them up in a bucket with a lid for her breakfast…). I love your integrated pest management stragegy and saving your energy for the food pests is our ethos as well. Thank you for those lovely photos and another great post :)

  3. says

    One of our batches of chickens didn’t used to eat them so hubby would squish them on the ground which always grossed me out. Luckily, a different batch of chickens would eat them, so no squishing. :}

    We’d not even seen any in the last couple of years.

  4. Carlee O'Dell says

    I worked with tobacco hornworms for many years. When the eggs hatch, a tiny larva emerges. As it grows, it molts its skin, and becomes a larger larva. These stages are called instars. The hornworm has 5 instars and, after the 5th instar, it pupates. After a period of time, the moth emerges. The larva in the second picture has been injured and the black is its blood (hemolymph) which turns that color when exposed to air.

  5. says

    I just figured out the difference between tobacco and tomato hornworms myself – had one eating my tomato plant but the lack of chevron patterning had me hunting further afield for ID. I moved it off the tomato and tossed it over the fence where it will either find other suitable forage or perhaps become bird food. I appreciate your philosophy when it comes to pest management. My husband and I disagree about when/if to spray – one of the few ongoing conflicts between us. He’s a physician and the West Nile virus showing up in 1 of 4 mosquitoes in our area crossed a line.

  6. alice schrade says

    I had a picture of a tomato hornworm with the little wasps connected to it. So yucky. If I find it I’ll send it. The wasps kill it , but fortunately i don’t know how.Do they suck it to death???

    • says

      Hi, Alice. Those are probably braconid wasps (which lay eggs on the hornworm). They are called parasitoids, and usually kill their host in the process of using them as a place to lay those eggs. As the eggs (which are actually inserted slightly under the skin of the hornworm) hatch, the newborns use the body of the caterpillar as their first meal. Like this.

  7. says

    Every couple of days we head out to our tomato patch and have a picking party. Once we get a small bucket full, we dump them out for our chickens and they go wild eating up every last one and usually within just a couple minutes. Then the chickens patiently wait the next time they see us at the tomato plants because they seem to know what is coming.

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