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Bug of the Week: Tobacco Hornworm

Add another caterpillar to Caterpillar Central from last week.

We found this brave caterpillar is feeding on a jalapeno pepper plant.

It is the tobacco hornworm, Manduca sexta, often confused with the tomato hornworm (Manduca quinquemaculata). The tobacco hornworm has straight white lines on its sides. The tomato hornworm has V-shaped markings.

It gets its name "hornworm" from the thorn-like projection at the rear of the caterpillar. The horn is not dangerous in any way. The caterpillars are perfectly harmless, except to plants.

Notice its three pairs of true legs right next to the head. The rest are fleshy prolegs.

When it finishes eating, the larva will drop off the plant and dig into the soil to pupate. The adult moth is called a hawkmoth or sphinx moth. It flies at night and isn't seen much during the day.

Tobacco hornworms are easy to raise and are great subjects for science activities with children.

The University of Arizona's Manduca Project website has a wealth of information about the life cycle, techniques for rearing Manduca, lesson plans (including cool science projects) and videos. Go check it out!

2 thoughts on “Bug of the Week: Tobacco Hornworm

  1. maryanne meehan

    I have four Tomato worms, large green ones. I would like to raise them to a moth. Any help would be appreciated. Thank you, Maryanne

  2. Roberta

    Maryanne,

    As you have probably already discovered, tomato hornworms eat a lot of foliage. You will need to keep giving them leaves until they are ready to pupate.

    When the caterpillars are ready to pupate, they will start what is called the wandering phase. They will quit eating, and start to move about the container in a way that could be described as restless. At that time, you will need to give them some soil to dig into. Clean potting soil is a good choice. Put them into a container with at least three inches of soil, enough so they can dig into it and covr themselves. The caterpillars will dig a chamber and pupate inside. The pupa will look like a reddish-brown to dark brown cigar shape.

    At that point it is basically a waiting game. Keep the soil slightly moist (don't let it dry out completely).

    See the post about raising caterpillars for a lot more details http://blog.growingwithscience.com/2008/09/raising-caterpillars/

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