Q:Β I found these in my garden. They are eating my tomatoes and eggplants. What is the best natural way to get rid of these critters?
A:Β These are tobacco hornworms (Manduca sexta). From the photo, you are already using the best natural method of getting rid of hornworms. Picking them off is as effective as any pesticide you might use. This is sometimes a challenge because they are the same color as the plant. Just look for damaged or missing leaves and they wonβt be too far away. You can just toss them aside or feed them your chickens if you have chickens. The trick is to examine your plants once a week so you catch them while they are still small and not eating as much. If you donβt get a thrill from the hunt and want to try something else, the organic insecticide Bacillus thuringiensis (Bt) is effective against the very small caterpillars. It is sometimes sold under the brand name Dipel. Simply apply it to the foliage as directed. This strain of Bt is toxic to caterpillars but nobody else. It may require repeat applications during the caterpillar-growing season because rain will wash it off the leaves and it degrades in the sun. Also, planting a variety of flowering plants around your vegetable garden will bring in some beneficial insects that may parasitize these caterpillars. The wasps that sting them feed on the pollen in your flowering plants and lay their eggs in the caterpillars.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed to tucsongardensage@gmail.com
