Bugs That Eat Dill



Few pests or diseases harm dill (Anethum graveolens), but aphids sometimes suck its sap, and tomato hookworms and anise swallowtail butterfly caterpillars eat its stems and foliage. An annual plant, dill provides aromatic leaves and seeds for the kitchen, and decorates ornamental gardens with its delicate, blue-green foliage and yellow summer flowers. Dill also attracts beneficial insects, such as lacewings, hover flies, ladybugs and other pest predators. Cultural control methods and biological controls eliminate the bugs that eat it.

Aphid Infestation

Aphids infest dill leaves and shoot tips, causing deformed and stunted growth. Small, pear-shaped insects, aphids eat by sucking sap from plants, which prevents them from growing healthily. A heavy aphid infestation can kill young dill plants. Aphids also excrete a sticky honeydew that turns black and sooty, making plants look unsightly. Squirting a strong jet of water at aphids washes them away. Turn the garden hose spray attachment to the strong jet setting or put your thumb over the end of an open garden hose, and hose dill plants from a distance of 3 to 4 inches, holding the soft foliage steady with your other hand. Hose the plants every three or four days as needed, and avoid feeding dill with high nitrogen fertilizers, which encourage aphid infestations.

Tomato Hornworms

Tomato hornworms, which have a characteristic horn at their rear ends, eat dill leaves and stems. Growing up to 4 inches long, tomato hornworms are sometimes difficult to see because of their striped patterning, but large black droppings on the ground below dill plants signal their presence. Examine dill plants for caterpillars every two or three days, and destroy them by cutting them in half or sealing them in a plastic bag and putting the bag in the trash. Dig up the soil where dill plants grew at the end of the growing season and destroy any cocoons you find.

Anise Swallowtail Caterpillars

If you love seeing butterflies in your garden, some dill-eating bugs you may not wish to control are caterpillars of the anise swallowtail butterfly. Anise swallowtail caterpillars are green or yellow-green and have spotted bands circling their bodies. The butterflies feature white or yellow patterning on their black, swallow-shaped wings, with black-centered, yellow-orange eyespots on their tails. Females lay single pale brown eggs on dill plants. Examining plants and scraping these off, and picking off caterpillars, provides control. Anise swallowtails aren't currently endangered.

Biological Control

Treating dill with Bacillus thuringiensis, a biological control, kills young caterpillars that eat it. Biological controls are natural predators or parasites that kill pests but are usually harmless to humans and other organisms. Bacillus thuringiensis, or Bt, is a microbe that attacks caterpillars. It controls small caterpillars but may not affect large caterpillars, and it is ineffective on eggs, cocoons, adult butterflies and moths. Dilute Bt at a rate of 1 tablespoon to 1 gallon of water and spray all plant parts, repeating weekly as needed, or apply according to the manufacturer's instructions.

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