The Tomato Hornworm

The garden is in full swing, more lovely every day. I am a big fan of annuals or tender perennials and shrubs, especially those that have night fragrance. Hand in hand with this type of garden are the night moths, swooping and sipping nectar, drawn by the fragrance and food for their young. One of their favorites are the flowering tobacco plants, or nicotiana. It's a source of food for the tomato hornworm larvae and a nectar source for the adult hornworm or sphinx moth. Since the flowering tobacco has been volunteering itself in my raised beds, there is no soil disturbance and the hornworms are able to survive as pupae in the stable soil. We do have tomatoes in the ground, but the tiller turns the soil where they grow, killing any pupae that would normally survive the winter. Bottom line, I have lots and lots of tomato hornworms in various stages of growth and they bother me nary a bit. In fact I'm happy to have them just so I can enjoy the sphinx moth.

For most people and any tomato farmer, the tomato hornworm is a pest. They do have a tremendous appetite, making quick work of tomato plants, the occasional potato and other members of the Solanaceae family. The proper name for this pest is Manduca quinquemaculata, the name means, I chew and have five spots (which are on its belly). There are seven stripes down the sides and some breathing holes that look like black dots in between.

It's not unusual to find a caterpillar with little cocoons on its back. These are non-stinging parasitoid wasps, they lay the eggs on a live hornworm and the young feed, killing the hornworm in a "not so nice" way. 

 A gardener's advice - always leave these paratisized caterpillars because they will release beneficial wasps. 

The real reward after all of this, if they do survive, is the adult Sphinx or hawk moth. The wing span can be five inches and they manuver with amazing agility, seeking nectar as night descends. The whirring of the wings is like a hummingbirds, you always know when they are near. There may be two broods in one summer and it does seem that there are more and more as we move into August and September. Like a hummingbird they are difficult to photograph, add the diminished light and it's almost impossible. 

I'm going to try harder to get some better photographs of the adults because I think my summer garden will be full of them.

Comments

[Peggy Riccio]

I just found a tomato hornworm on my tomato plant (and was even going to write about it) but never linked it with my flowering tobacco plants, good to know, great article!

[karen]

Peggy,
This is the first year that they have defoliated my flowering tobacco, at least in one bed. I think I will have lots of lovely big sphinx moths.
Thanks for the comment.