In My Backyard - Meet the Tomato Hornworm

Note the red horn on its tail.

When it comes to his tomato plants my husband is fanatic. Do they have enough water? Are the blossoms forming fruit? What's the spot on the bottom of the tomato? Are they ready to pick? And then this past week: What's that green bug with the white eggs on its back?

He spent some time on the internet and came up with the answer. It is a tomato hornworm and the eggs aren't really eggs but tiny cocoons of a small type of wasp. I thought he was exaggerating until he called me out to the deck where our tomatoes and peppers grow in special earth boxes that he ordered this year along with a kit that contained the right amounts of fertilizer.

The hornworm we found was fascinating so of course I had to look it up and check it out myself. They grow anywhere from three to five inches (depending upon which site you read). Eventually they become a brown moth. They like only certain plants and favor the tomato the most, thus the name. They will burrow into the soil for their pupae stage and can have two generations in one summer as well as winter-over in the soil.

Against the green leaves it is difficult to see them unless the wasps have found them and laid their eggs there to hatch into larva which actually feed off of the hornworm. They then spin their small white cocoons and eventually emerge. Meanwhile the hornworm is spent from being food for the wasps. Several sites I visited said to leave the hornworms with the wasp cocoons alone as the wasps will help to control the hornworm population.

Uncontrolled, the hornworms will defoliate your tomato plants, feeding off the tender new leaves first and working their way down. Without the wasps, it is suggested you pick the worms off the plants and put them in a soapy water solution (or smash them if you are so inclined).

Every year there is something new to discover in our backyard and we certainly don't have to travel far to see it.