The tomato hornworms have arrived!

We knew this day would come, but it didn't make it any less alarming when we found the first tomato hornworm of the season.  These caterpillars can be up to 4 1/2 inches long and 1/2 inch in diameter!  They are bright green in color and easily camouflage with the branches of the tomato plants.  As their name would suggest, tomato hornworms have a large black horn on their tails.  Hornworms are the larval stage of the five-spotted hawkmoth (Manduca quinquemaculata) which has an impressive 4-5 inch wingspan.  The moths lay eggs on the underside of tomato leaves.  A week later, the eggs hatch and larval caterpillars feed on the tomato plants for about a month.  Then, the hornworms pupate in the soil until the following spring, at which point they will emerge as a moth.

The tomato hornworms are voracious feeders and can defoliate a tomato plant.  The only recommended method of managing the hornworm population is handpicking.  For those brave enough, the hornworms can be picked off the plants and squished or dropped into a bucket of soapy water.  For those who like to keep their distance, we have a set of long-handled grass shears which can be used to remove the tomato hornworms without touching them!  Tilling the soil in the fall can significantly reduce the tomato hornworm population for the following year, because it kills the larvae and pupae living in the soil.  There is a species of parasitic wasp that infects tomato hornworms and keeps the population in control, but we have not seen any evidence of the wasps in our garden yet.  Tomato hornworms infected by the parasitic wasps have small white projections all over their backs.  If we see any infected hornworms, we won't remove them so that it will encourage growth of the parasitic wasp population.
For now, tomato hornworm removal duty has been added to our list of daily garden activities, but luckily they have a short season and will only stick around for a few more weeks.
Our "tomato hornworm removal tool"


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